#include <bits/stdc++.h>

using namespace std;
#define ll long long

long sumOfGroup(int k) {
    // Return the sum of the elements of the k'th group.
    ll int first = (ll)k * (ll)k;
    first = first - k + 1;
    
    ll int last = (ll)(k + 1) * (ll)(k + 1);
    last = last - k;
    
    ll int sum = 0;
        
    while(first != last){
        sum = sum + first;
        first += 2;
    }
    
    return sum;
}

int main() {
    int k;
    cin >> k;
    long answer = sumOfGroup(k);
    cout << answer << endl;
    return 0;
}