#include <bits/stdc++.h>

using namespace std;

long sumOfGroup(int k) {
    // Return the sum of the elements of the k'th group.
    vector<vector<int>> group;
    long value = 1;
    int i;
    for ( i=0;i<k;i++ )
    {
        vector<int> temp;
        for ( int j=0;j<=i;j++)
        {
            temp.push_back(value);
            value += 2;
        }
        group.push_back(temp);
    }
    long sum = 0;
    for ( i=0;i<k;i++ )
    {
        sum += group[k-1][i];
    }
    return sum;
}

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