#include <iostream>

using namespace std;

class matrix{
public:
    matrix(int);
    void getMatrixNumbers();
    int mainDiameter();

private:
    int x[100][100];
    int i, j, n;
};

/*
 * sazande
 * ye count migire ke tool o arze matrixe
 */
matrix::matrix(int count){
    n = count;
}

/*
 * In tabe kolle adadaye matrix ro az karbar migire
 */
void matrix::getMatrixNumbers(){
    for(int i=0;i<n;i++)
        for(int j=0;j<n;j++){
            int n;
            cout << "Please enter number for row:" << i << "  column:" << j << " : ";
            cin >> n;
            x[i][j] = n;
        }
}

/*
 * Jame gotre far'io bar migardune
 */
int matrix::mainDiameter(){
    int sum = 0;

    for(int i=0;i<n;i++)
        for(int j=0;j<n;j++)
            if(i+j==n+1)
                sum += x[i][j];

    return sum;
}

int main()
{
    int n;          //andazeye matrix
    cout << "Please enter matrix dimention: ";
    cin>>n;         //az karbar migirim
    matrix m(n);            //tarife matrix
    m.getMatrixNumbers();
    int d = m.mainDiameter();

    cout << "matrix diameter is: " << d << endl;
}