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