pct_of

#include <fstream>
#define N 1002
using namespace std;
int a[N][N],b[N][N],c[N];

int main()
{
    int n,k;
    ifstream f("pct.in");
    f>>n>>k;
    int x,y;
    for(int i=1;i<=n;++i)
        f>>x>>y,a[x+1][y+1]=1;
    f.close();
    for(int i=1;i<=1001;++i)
        for(int j=1;j<=1001;++j)
        	c[j]+=a[i][j],b[i][j]=b[i][j-1]+c[j];
    int nr,maxim=0;
    for(int i=1;i<=1001-k;++i)
        for(int j=1;j<=1001-k;++j)
        {
            nr=b[i+k][j+k]-b[i+k][j-1]-b[i-1][j+k]+b[i-1][j-1];
            if(nr>maxim)
                maxim=nr;
        }
    ofstream g("pct.out");
    g<<maxim;
    g.close();
    return 0;
}