func_code_string: #include <bits/stdc++.h>   using namespace std;   const long long mod = 1000000000 + 7;   const int N = 10000001;   long long dp[N];   int main() {     dp[1] = 0;     dp[2] = 3;     for (int i = 3; i < N; i++) dp[i] = (dp[i - 2] * 3 + dp[i - 1] * 2) % mod;     int n;     while (scanf( %d , &n) != EOF) printf( %lld n , dp[n]);     return 0;   }   