#!/usr/bin/env python3
# -*- coding: utf-8 -*-

import functools

MODULUS = 10 ** 9 + 7


@functools.lru_cache(maxsize=None)
def count_courses(n):
    if n == 1:
        return 1
    elif n == 2:
        return 2
    elif n == 3:
        return 2
    else:
        return (count_courses(n - 2) + count_courses(n - 3)) % MODULUS


if __name__ == "__main__":
    print(count_courses(int(input())))