Maximum sum on a torus UVA - 10827

#include <iostream>
#include <cstring>
#include <algorithm>
using namespace std;
const int N=300;

int a[N][N],s[N][N],n;

 int S(int x1,int y1,int x2,int y2){
 	return s[x2][y2]+s[x1-1][y1-1]-
 	s[x1-1][y2]-s[x2][y1-1];
 }
 void sov(){
 	int i,j;
 	memset(s,0,sizeof s);
 	cin>>n;
 	for(i=1;i<=n;++i)
 	 for(j=1;j<=n;++j) cin>>a[i][j];
 	
 	for(i=1;i<=2*n;++i)
 	 for(j=1;j<=2*n;++j){
 	 	a[i][j]=a[(i-1)%n+1][(j-1)%n+1];
 	 }
 	for(i=1;i<=2*n;++i)
 	 for(j=1;j<=2*n;++j){
 	 	s[i][j]=s[i-1][j]+s[i][j-1]-
 	 	s[i-1][j-1]+a[i][j];
 	 }	
 	 int ans=0;
 	 for(i=1;i<=2*n;++i)
 	  for(j=1;j<=2*n;j++)
 	 	for(int k=i;k<=min(i+n-1,2*n);k++)
 	 	 for(int l=j;l<=min(j+n-1,2*n);l++){
 	 	 	ans=max(ans,S(i,j,k,l));
 	 	 }
 	 cout<<ans<<endl;
 }
 signed main(){
 	int tes; cin>>tes;
 	while(tes--)
 	sov();
 }