infoarena informatica de performanta

#include<fstream.h>
int main()
{unsigned long n,a[501][501],i,j,nr=0,dif,s,s1=0;
ifstream f("numere.in");
ofstream g("numere.out");
f>>n;
for (i=1; i<=n; i++)
	for(j=1; j<=n; j++)
   	{f>>a[i][j];
       	 if (a[i][j]==0)
       		nr++;
      	  s1+=a[i][j];
      	 }
s=(n*n*(n*n+1))/2;
dif=s-s1;
i=(dif+1)/nr-1;
j=i+nr-1;
g<<i<<" "<<j;
f.close();
g.close();
return 0;
}