#include <iostream>
#include <vector>

using lint = long long;
constexpr lint MOD = 1e9 + 7;

void solve() {
    int n;
    std::cin >> n;

    if (n < 3) {
        std::cout << n << std::endl;
        return;
    }

    lint a = 0, b = 0, c = 1;
    while (n--) {
        lint d = (a + b) % MOD;
        a = b;
        b = c;
        c = d;
    }

    std::cout << (a + b + c) % MOD << std::endl;
}

int main() {
    std::cin.tie(nullptr);
    std::ios::sync_with_stdio(false);

    solve();

    return 0;
}