#include <bits/stdc++.h>
#define MOD 1000000007
typedef long long ll;
using namespace std;

ll N;

int main(void){
    
    cin >> N;
        
    ll a = 1, b = 0, c = 0;
    for(int i = 0; i < N; ++i){
        int A = a, B = b, C = c;
        a = (B + C) % MOD;
        b = A;
        c = B;
    }
    
    cout << (a + b + c) % MOD << endl;
    
    return 0;
}