// UUID: cb165ea2-d315-4191-bf47-b136af46ff88
#include <bits/stdc++.h>
using namespace std;

void solve() {
    int n;
    cin >> n;

    vector<int> dp(n + 1, 0);

    dp[0] = 0;
    dp[1] = 2;
    dp[2] = 11;

    for (int i = 3; i <= n; i++) {
        dp[i] = dp[i-1] * 2 + dp[i-2] * 2;
    }

    cout << dp[n];
    return;
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    int t = 1;
    //cin >> t;
    while (t--) {
        solve();
    }
    return 0;
}