WA on #12求条

#include<bits/stdc++.h>
#define f(a,b,c) for(int a=b;a<=c;a++)
using namespace std;
int n,m,a,b,x,y,z,ans,s[10005][10005];
int main(){
	ios::sync_with_stdio(0);
	cin.tie(0),cout.tie(0);
	cin>>n>>m;
	f(i,0,n){
		cin>>x>>y>>z;
		s[x+1][y+1]=z;
	}
	f(i,1,5005)
		f(j,1,5005)
			s[i][j]=s[i-1][j]+s[i][j-1]-s[i-1][j-1]+s[i][j];
	f(i,m,5005)
		f(j,m,5005)
			ans=max(ans,s[i][j]-s[i][j-m]-s[i-m][j]+s[i-m][j-m]);
	cout<<ans;
}