#include <iostream>
using namespace std;
const long long mod = 1000000007;
long long dp[1000005][4];
int main(){
    int n;cin>>n;
    dp[1][1] = 1;
    dp[2][2] = 1;
    dp[3][3] = 1;
    
    for(int i = 1; n >= i; i++){
        for(int j = 1; 4 > j; j++){
            if(j!=1)dp[i+1][1] = (dp[i+1][1]+dp[i][j])%mod;
            if(j!=2)dp[i+2][2] = (dp[i+2][2]+dp[i][j])%mod;
            if(j!=3)dp[i+3][3] = (dp[i+3][3]+dp[i][j])%mod;
        }
    }
    cout << (dp[n][1]+dp[n][2]+dp[n][3])%mod << endl;
    
}