Muro.cpp

#include<bits/stdc++.h>
using namespace std;
const int maxn = 1e4+10;
const int mod = 1e9+7;
int n;
long long dp[maxn];

int main() {
    cin >> n;
    dp[0] = 1;
    dp[1] = 1;
    dp[2] = 5;
    for(int i = 3; i <= n; i++) {
        dp[i] = (1*dp[i-1]+4*dp[i-2]+2*dp[i-3])%mod;
    }

    cout << dp[n] << endl;
}