#include <bits/stdc++.h>
using namespace std;

long long mod = 1000000007;

int main() {

    long long n;
    cin >> n;

    vector<long long> dp(n+1, 0);
    dp[0] = 1;

    long long t = 1;
    for(int i = 1; i < n+1; ++i) {
        dp[i] = (t-dp[i-1])%mod;
        t = (t*3)%mod;
    }

    cout << dp[n] << endl;

}