#include <iostream> 
#include <algorithm> 
#include <cstring> 
#include <cstdio>
#include <vector> 
#include <queue> 
#include <cstdlib> 
#include <iomanip>
#include <cmath> 
#include <ctime> 
#include <map> 
#include <set> 
using namespace std; 
#define lowbit(x) (x&(-x)) 
#define max(x,y) (x>y?x:y) 
#define min(x,y) (x<y?x:y) 
#define MAX 100000000000000000 
#define MOD 1000000007
#define pi acos(-1.0) 
#define ei exp(1) 
#define PI 3.141592653589793238462
#define ios() ios::sync_with_stdio(false)
#define INF 1044266558
#define mem(a) (memset(a,0,sizeof(a)))
typedef long long ll;
int n,R;
struct Node
{
    int x;
    int y;
}node[1005],pos[1005];
bool cmp(Node a,Node b)
{
    return a.x<b.x;
}
int main()
{
    while(scanf("%d%d",&n,&R)!=EOF)
    {
        int ans=0,cnt=0,inf=0,start,end,tot=0;
        for(int i=0;i<n;i++)
        {
            scanf("%d%d",&node[i].x,&node[i].y);
        }
        sort(node,node+n,cmp);
        for(int i=0;i<n;i++)
        {
            tot=0;
            start=node[i].x,end=node[i].x+R;
            for(int j=i;j<n;j++)
            {
                if(node[j].x>=start && node[j].x<=end)
                {
                    pos[tot].x=node[j].y;
                    pos[tot++].y=1;
                    pos[tot].x=node[j].y+R+1;
                    pos[tot++].y=-1;
                }
            }
            sort(pos,pos+tot,cmp);
            for(int j=0;j<tot;j++)
            {
                cnt+=pos[j].y;
                inf=max(inf,cnt);
            }
            ans=max(inf,ans);
        }
        printf("%d\n",ans);
    }
    return 0;
}