#include <bits/stdc++.h>

using namespace std;

long sumOfGroup(int n) {
    long num = 1,sum=0;
    for(int i =0;i<n;i++)
    {
        if(i == n-1)
        {
            for(int j=0;j<i+1;j++){
                //cout<<num<<endl;
                sum = sum + num;
                num+= 2;
            }
                
        }
        else
        {
            for(int j=0;j<i+1;j++)
            {
                num+= 2;
            }
        }        
    }
    return sum;
}

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