# include<iostream> using namespace std; int main(){ int n,a[10][10],x=0; cin>>n; for(int i=0;i<n;i++){ for(int j=0;j<n;j++){ cin>>a[i][j]; if(i==j||i+j==n-1)x+=a[i][j]; } } cout<<x; return 0; }