630C - Lucky Numbers - CodeForces Solution

// Math 39
#include <bits/stdc++.h>
using namespace std;
void solve()
{
    long long n;
    cin >> n;
    long long ans = 0;
    while (n > 0)
    {
        long long x = pow(2, n) + 0.5;
        ans += x;
        n--;
    }
    cout << ans << endl;
}
int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    cout.tie(NULL);
    long long t = 1;
    // cin >> t;
    while (t--)
    {
        solve();
    }
    return 0;
}