#include <bits/stdc++.h>
using namespace std;
 
typedef long long ll;
typedef long double ld; 
typedef double db; 
typedef string str; 

typedef pair<int, int> pi;
typedef pair<ll,ll> pl; 
typedef pair<ld,ld> pd; 
#define mp make_pair
#define f first
#define s second

typedef vector<int> vi; 
typedef vector<ll> vl; 
typedef vector<ld> vd; 
typedef vector<str> vs; 
typedef vector<pi> vpi; 
typedef vector<pl> vpl; 
typedef vector<pd> vpd; 

#define sz(x) (int)x.size()
#define all(x) begin(x), end(x)
#define rall(x) (x).rbegin(), (x).rend() 
#define rsz resize
#define ins insert 
#define ft front() 
#define bk back() 
#define pf push_front 
#define pb push_back
#define eb emplace_back 
#define lb lower_bound 
#define ub upper_bound 

#define FOR(i,a,b) for (int i = (a); i < (b); ++i)
#define F0R(i,a) FOR(i,0,a)
#define ROF(i,a,b) for (int i = (b)-1; i >= (a); --i)
#define R0F(i,a) ROF(i,0,a)
#define trav(a,x) for (auto& a: x)

const int MOD = 1e9+7; // 998244353; // = (119<<23)+1
const int MX = 5e4+5; 
const ll INF = 1e18; 
const ld PI = 4*atan((ld)1); 
const int xd[4] = {0,1,0,-1}, yd[4] = {1,0,-1,0}; 

template<class T> bool ckmin(T& a, const T& b) { 
	return a > b ? a = b, 1 : 0; }
template<class T> bool ckmax(T& a, const T& b) { 
	return a < b ? a = b, 1 : 0; }
mt19937 rng((uint32_t)chrono::steady_clock::now().time_since_epoch().count());

#include <ext/pb_ds/tree_policy.hpp>
#include <ext/pb_ds/assoc_container.hpp>
using namespace __gnu_pbds;

template <class T> using Tree = tree<T, null_type, less<T>, 
	rb_tree_tag, tree_order_statistics_node_update>; 
// change null_type for map
#define ook order_of_key
#define fbo find_by_order

void treeExample() {
	Tree<int> t, t2; t.insert(8);
	auto it = t.insert(10).f; assert(it == t.lb(9));
	assert(t.ook(10) == 1); assert(t.ook(11) == 2);
	assert(*t.fbo(0) == 8);
	t.join(t2); // assuming T < T2 or T > T2, merge t2 into t
}

namespace input {
	template<class T> void re(complex<T>& x);
	template<class T1, class T2> void re(pair<T1,T2>& p);
	template<class T> void re(vector<T>& a);
	template<class T, size_t SZ> void re(array<T,SZ>& a);

	template<class T> void re(T& x) { cin >> x; }
	void re(double& x) { string t; re(t); x = stod(t); }
	void re(ld& x) { string t; re(t); x = stold(t); }
	template<class T, class... Ts> void re(T& t, Ts&... ts) { 
		re(t); re(ts...); 
	}

	template<class T> void re(complex<T>& x) { T a,b; re(a,b); x = cd(a,b); }
	template<class T1, class T2> void re(pair<T1,T2>& p) { re(p.f,p.s); }
	template<class T> void re(vector<T>& a) { F0R(i,sz(a)) re(a[i]); }
	template<class T, size_t SZ> void re(array<T,SZ>& a) { F0R(i,SZ) re(a[i]); }
}

using namespace input;

namespace output {
	void pr(int x) { cout << x; }
	void pr(long x) { cout << x; }
	void pr(ll x) { cout << x; }
	void pr(unsigned x) { cout << x; }
	void pr(unsigned long x) { cout << x; }
	void pr(unsigned long long x) { cout << x; }
	void pr(float x) { cout << x; }
	void pr(double x) { cout << x; }
	void pr(ld x) { cout << x; }
	void pr(char x) { cout << x; }
	void pr(const char* x) { cout << x; }
	void pr(const string& x) { cout << x; }
	void pr(bool x) { pr(x ? "true" : "false"); }
	template<class T> void pr(const complex<T>& x) { cout << x; }
	
	template<class T1, class T2> void pr(const pair<T1,T2>& x);
	template<class T> void pr(const T& x);
	
	template<class T, class... Ts> void pr(const T& t, const Ts&... ts) { 
		pr(t); pr(ts...); 
	}
	template<class T1, class T2> void pr(const pair<T1,T2>& x) { 
		pr("{",x.f,", ",x.s,"}"); 
	}
	template<class T> void pr(const T& x) { 
		pr("{"); // const iterator needed for vector<bool>
		bool fst = 1; for (const auto& a: x) pr(!fst?", ":"",a), fst = 0; 
		pr("}");
	}
	
	void ps() { pr("\n"); } // print w/ spaces
	template<class T, class... Ts> void ps(const T& t, const Ts&... ts) { 
		pr(t); if (sizeof...(ts)) pr(" "); ps(ts...); 
	}
	
	void pc() { pr("]\n"); } // debug w/ commas
	template<class T, class... Ts> void pc(const T& t, const Ts&... ts) { 
		pr(t); if (sizeof...(ts)) pr(", "); pc(ts...); 
	}
	#define dbg(x...) pr("[",#x,"] = ["), pc(x);
}

using namespace output;

namespace io {
	void setIn(string s) { freopen(s.c_str(),"r",stdin); }
	void setOut(string s) { freopen(s.c_str(),"w",stdout); }
	void setIO(string s = "") {
		ios_base::sync_with_stdio(0); cin.tie(0); // fast I/O
		// cin.exceptions(cin.failbit); // ex. throws exception when you try to read letter into int
		if (sz(s)) { setIn(s+".in"), setOut(s+".out"); } // for USACO
	}
}

using namespace io;

struct mi {
	typedef decay<decltype(MOD)>::type T;
	T val; 
	explicit operator T() const { return val; }
	mi() { val = 0; }
	mi(ll v) { 
		val = (-MOD <= v && v <= MOD) ? v : v % MOD;
		if (val < 0) val += MOD;
	}
	friend bool operator==(const mi& a, const mi& b) { 
		return a.val == b.val; }
	friend bool operator!=(const mi& a, const mi& b) { 
		return !(a == b); }
	friend bool operator<(const mi& a, const mi& b) { 
		return a.val < b.val; }
	friend void re(mi& a) { ll x; re(x); a = mi(x); }
	friend void pr(const mi& a) { pr(a.val); }
	friend ostream& operator<<(ostream& os, const mi& a) { 
		return os << a.val; }
   
	mi operator-() const { return mi(-val); }
	mi& operator+=(const mi& m) { 
		if ((val += m.val) >= MOD) val -= MOD; 
		return *this; }
	mi& operator-=(const mi& m) { 
		if ((val -= m.val) < 0) val += MOD; 
		return *this; }
	mi& operator++() { return *this += 1; }
	mi& operator--() { return *this -= 1; }
	friend mi operator+(mi a, const mi& b) { return a += b; }
	friend mi operator-(mi a, const mi& b) { return a -= b; }

	mi& operator*=(const mi& m) { 
		val = (ll)val*m.val%MOD; return *this; }
	friend mi pow(mi a, ll p) {
		mi ans = 1; assert(p >= 0);
		for (; p; p /= 2, a *= a) if (p&1) ans *= a;
		return ans;
	}
	friend mi inv(const mi& a) { 
		assert(!(a == 0)); return pow(a,MOD-2); }
	mi& operator/=(const mi& m) { return (*this) *= inv(m); }
	friend mi operator*(mi a, const mi& b) { return a *= b; }
	friend mi operator/(mi a, const mi& b) { return a /= b; }
};
typedef pair<mi,mi> pmi;
typedef vector<mi> vmi;
typedef vector<pmi> vpmi;

// Either globally or in a single class:
static char buf[450 << 20];
void* operator new(size_t s) {
	static size_t i = sizeof buf; assert(s < i);
	return (void*)&buf[i -= s];
}
void operator delete(void*) {}

const int SZ = MX;
template<class T> struct node {
	T val = 0; node<T>* c[2];
	node() { c[0] = c[1] = NULL; }
	void upd(int ind, T v, int L = 0, int R = SZ-1) { // add v
		if (L == ind && R == ind) { val += v; return; }
		int M = (L+R)/2;
		if (ind <= M) {
			if (!c[0]) c[0] = new node();
			c[0]->upd(ind,v,L,M);
		} else {
			if (!c[1]) c[1] = new node();
			c[1]->upd(ind,v,M+1,R);
		}
		val = 0; F0R(i,2) if (c[i]) val += c[i]->val;
	}
	T query(int lo, int hi, int L = 0, int R = SZ-1) { // query sum of segment
		if (hi < L || R < lo) return 0;
		if (lo <= L && R <= hi) return val;
		int M = (L+R)/2; T res = 0;
		if (c[0]) res += c[0]->query(lo,hi,L,M);
		if (c[1]) res += c[1]->query(lo,hi,M+1,R);
		return res;
	}
	void UPD(int ind, node* c0, node* c1, int L = 0, int R = SZ-1) {
		if (L != R) {
			int M = (L+R)/2;
			if (ind <= M) {
				if (!c[0]) c[0] = new node();
				c[0]->UPD(ind,c0?c0->c[0]:NULL,c1?c1->c[0]:NULL,L,M);
			} else {
				if (!c[1]) c[1] = new node();
				c[1]->UPD(ind,c0?c0->c[1]:NULL,c1?c1->c[1]:NULL,M+1,R);
			}
		} 
		val = (c0?c0->val:0)+(c1?c1->val:0);
	}
};

template<class T> struct Node {
	node<T> seg; Node* c[2];
	Node() { c[0] = c[1] = NULL; }
	void upd(int x, int y, T v, int L = 0, int R = SZ-1) { // add v
		if (L == x && R == x) { seg.upd(y,v); return; }
		int M = (L+R)/2;
		if (x <= M) {
			if (!c[0]) c[0] = new Node();
			c[0]->upd(x,y,v,L,M);
		} else {
			if (!c[1]) c[1] = new Node();
			c[1]->upd(x,y,v,M+1,R);
		}
		seg.upd(y,v); // only for addition
		// seg.UPD(y,c[0]?&c[0]->seg:NULL,c[1]?&c[1]->seg:NULL);
	}
	T query(int x1, int x2, int y1, int y2, int L = 0, int R = SZ-1) { // query sum of rectangle
		if (x1 <= L && R <= x2) return seg.query(y1,y2);
		if (x2 < L || R < x1) return 0;
		int M = (L+R)/2; T res = 0;
		if (c[0]) res += c[0]->query(x1,x2,y1,y2,L,M);
		if (c[1]) res += c[1]->query(x1,x2,y1,y2,M+1,R);
		return res;
	}
};

Node<int> O;
int N,T;
vpi v;

void updH(int x, int y) {
	if (v[x].s != v[x+1].s) return;
	int a = min(v[x].f,v[x+1].f), b = max(v[x].f,v[x+1].f);
	O.upd(a+1,v[x].s,y), O.upd(b,v[x].s,-y);
}

void compress() {
	map<int,int> x,y;
	trav(t,v) x[t.f] = y[t.s] = 0;
	int co = 0; trav(t,x) t.s = ++co;
	co = 0; trav(t,y) t.s = ++co;
	trav(t,v) t.f = x[t.f], t.s = y[t.s];
}

int main() {
	setIO("mowing");
	re(N,T); v.rsz(N); re(v); compress();
	int l = 0, r = T; FOR(i,T,N-1) updH(i,1);
	ll ans = 0;
	F0R(i,N-1) if (v[i].f == v[i+1].f) {
		while (l <= i-T) updH(l++,1);
		while (r < N-1 && r < i+T) updH(r++,-1);
		int a = min(v[i].s,v[i+1].s), b = max(v[i].s,v[i+1].s);
		ans += O.query(1,v[i].f,a+1,b-1);
	}
	ps(ans);
	// you should actually read the stuff at the bottom
}

/* stuff you should look for
	* int overflow, array bounds
	* special cases (n=1?), slow multiset operations
	* do smth instead of nothing and stay organized
*/