# include<iostream> # include<iomanip> using namespace std; int main(){ int n,a[100][100],m=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){m+=a[i][j];continue;} if(i+j+1==n){m+=a[i][j];continue;} } } cout<<m; return 0; } /* 4 2 2 3 4 5 6 7 8 2 4 6 4 3 6 9 7 */