#include <iostream>
using namespace std;

int main()
    { int k;
      int j = 0;

    cout << "enter an odd number" << endl;
    cin >> k;

    if (k%2 == 1) { j = (k-2)*(k-2) + 2*(k-2) + 2;
     cout << j << endl;
}
    else { cout << "error" << endl;
}
}