from functools import reduce
from fractions import gcd
import math
import bisect
import itertools
import sys
sys.setrecursionlimit(10**7)
input = sys.stdin.readline
INF = float("inf")
MOD = 1000000007

# 処理内容
def main():
    N = int(input())
    
    dpk = [0] * N
    dpkk = [0] * N
    dpp = [0] * N
    dpk[0] = 1
    for i in range(N-1):
        dpk[i+1] = dpp[i]
        dpkk[i+1] = dpk[i]
        dpp[i+1] = (dpk[i] + dpkk[i]) % MOD
    
    print((dpk[N-1] + dpkk[N-1] + dpp[N-1]) % MOD)


if __name__ == '__main__':
    main()