Answer 1

#include <iostream>
using namespace std;

int main() {
int n;
cin>>n;
int a[n][n];
for(int i=0;i<n;i++)
{
for(int j=0;j<n;j++)
{
cin>>a[i][j];
}
}

//sum the elements
int sum=0;
for(int i=0;i<n;i++)
{
sum+=(a[i][i]+a[i][n-1-i]);
}
if(n%2)
{
n/=2;
sum-=a[n][n];
}
cout<<"sum of elements ="<<sum;
return 0;
}