#include <bits/stdc++.h>
#define rep(i,n) for(int i = 0; i < (n); ++i)
#define srep(i,s,t) for (int i = s; i < t; ++i)
#define drep(i,n) for(int i = (n)-1; i >= 0; --i)
using namespace std;
typedef long long int ll;
typedef pair<int,int> P;
#define yn {puts("Yes");}else{puts("No");}
#define MAX_N 200005

int main() {
    const ll MOD = 1000000007;
    int n; cin >> n;
    ll a[n+10] = {};
    a[0] = 1;
    a[1] = 1;
    a[2] = 2;
    srep(i,3,n+1){
        a[i] = a[i-1] + a[i-2] + a[i-3];
        a[i] %= MOD;
    }
    cout << a[n] << endl;
    return 0;
}