#include <iostream>
using namespace std;

int a, b, c, n;

int formula(int x)
{
    return ((c - 1)/2)*6;
}

int main()
{
    c = 1;
    a = 3;
    cin >> n;
    while (c < n)
    {
        b = formula(a)/2 + (a - formula(a))*2;
        ++c;
        a = b;
    }
    cout << a;
    return 0;
}