#include<iostream>
using namespace std;
int main(){ int n, a[21][21], dp=0, ds=0; cin>>n; for (int i=1; i<=n; i++) for (int j=1; j<=n;j++) { cin>>a[i][j]; if (i==j) dp+=a[i][j]; if (i+j==n+1) ds+=a[i][j]; } if (dp>ds) cout<<dp-ds; else cout<<ds-dp; return 0;}