#include <iostream>
using namespace std;


long long memo[3]={1,1,1};
//memo={kenPa,kenKen,paKen}, n=4
long long kp, kk, pk, ans;
int n;

long long dp(){
    switch(n){
        case 1:
            ans = 1;
            break;
        case 2:
            ans = 2;
            break;
        case 3:
            ans = 2;
            break;
        case 4:
            ans = 3;
            break;
        default:
            for(int i=4; i<n; i++){
                kp = memo[0];
                kk = memo[1];
                pk = memo[2];
                memo[0] = (kk+pk)%1000000007;
                memo[1] = pk;
                memo[2] = kp;
            }
            ans = (memo[0]+memo[1]+memo[2])%1000000007;
            break; 
    }
    return ans;
}

int main(){
    cin >> n;
    cout << dp() << endl;
    return 0;
}