#include <bits/stdc++.h>

using namespace std;

long sumOfGroup(int k) {
    // Return the sum of the elements of the k'th group.
    long n=1,ans=0;
    for(int i=1;i<=k;i++)
    {
        int j=i;
        if(i==k)
        {
            while(j-- > 0)
            {
                ans+=n;
                n+=2;
                
            }
            return ans;
        }
        while(j-- > 0)
        {
            n+=2;
            
        }
    }
    return ans;
}

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