#include <iostream>
using namespace std;
int v[20][20];
int main()
{
int n, i, j, suma=0;
cout << " n= "; cin >> n;
cout << " introdu " << n*n << " numere reale \n";
for (i=0; i<n; ++i)
{
for (j=0; j<n; ++j)
cin >> v[i][j];
}
for (i=0; i<n; ++i)
{
suma+=v[i][i]*v[i][i];
}
cout << " suma= " << suma << "\n";
return 0;
}