#include<iostream>
#include<cstdio>
#include<algorithm>
#include<cstring>
#include<cmath>
#define ll long long
using namespace std;
const int MN=5e5+5;
ll n,t,s[MN],ans,num;
struct point{ll x,y;}p[MN];
void write(ll n){if(n<0){putchar('-');write(-n);return;}if(n>9)write(n/10);putchar(n%10+'0');}
ll read(){ll x=0,f=1;char ch=getchar();while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();}while(ch>='0'&&ch<='9'){x=(x<<1)+(x<<3)+(ch^48);ch=getchar();}return x*f;}
bool cmp(point a, point b){return a.x==b.x?a.y<b.y:a.x<b.x;}
int main(){
    n=read();t=read();
    for(int i=1; i<=n; i++) p[i].x=read(),p[i].y=read();
    for(int i=1; i<=n; i++) s[i]=abs(p[i].x-p[i-1].x)+abs(p[i].y-p[i-1].y);\
    if(s[1]>2) write(0);
    else{
        num=t;ans=1;
        for(int i=2; i<=n; i++){
            if(s[i]<=num){
                num+=t-s[i];
                ans++;
            }
        }
        write(ans);
    }
    return 0;
}