#include<fstream>
#include<iostream>

using namespace std;

int n,i,j,s1=0,s2=0,a[10][10];
ifstream f("mp.in");

int main()
{ 
    f>>n;
    for(i=1;i<=n;i++)
      for(j=1;j<=n;j++)
        f>>a[i][j];
        
    for(i=1;i<=n;i++)
      for(j=1;j<=n;j++)
         if(i>j) s1=s1+a[i][j];
         else if(j>i) s2=s2+a[i][j]; 
    while(s1!=s2)
      if(s1>s2) s1=s1-s2;
      else s2=s2-s1;
    cout<<s1;          
    system("pause");
    return 0;      
}