#include<cstdio>

 #include<iostream>

 #include<algorithm>

 #include<cstring>

 #include<cmath>

 #include<queue>

 #include<map>

 using namespace std;

 #define MOD 1000000007

 const int INF=2e9;

 const double eps=1e-;

 typedef long long ll;

 #define cl(a) memset(a,0,sizeof(a))

 #define ts printf("*****\n");

 const int MAXN=;

 int n,m,tt;

 struct Node

 {

     int x,y;

     void in()

     {

         scanf("%d%d",&x,&y);

     }

 }node[MAXN];

 bool cmp(Node a,Node b)

 {

     return a.y<b.y;

 }

 int ans[MAXN],R,tot;

 int main()

 {

     int i,j,k;

     #ifndef ONLINE_JUDGE

     freopen("1.in","r",stdin);

     #endif

     while(scanf("%d%d",&n,&R)!=EOF)

     {

         for(i=;i<n;i++)

         {

             scanf("%d%d",&node[i].x,&node[i].y);

         }

         sort(node,node+n,cmp);

         int MAX=,e;

         for(i=;i<n;i++)

         {

             tot=;

             for(j=;j<n;j++)

             {

                 if(node[j].y>=node[i].y&&node[j].y<=node[i].y+R)

                     ans[tot++]=node[j].x;

             }

             sort(ans,ans+tot);

             ans[tot++]=INF;

             e=;

             for(j=;j<tot-;j++)

             {

                 while(ans[e]<=ans[j]+R) e++;

                 MAX=max(MAX,(e-j));

             }

         }

         printf("%d\n",MAX);

     }

 }