#ABC129C-TypicalStairs.py

#import list
from sys import stdin, setrecursionlimit
from functools import lru_cache

input = stdin.readline
setrecursionlimit(100000)

#constant
#N = int(input())
N, M = list(map(int,input().split()))
A = [int(input()) for _ in range(M)]

#variable

#function
@lru_cache(maxsize=1000)
def rootCount(position):
    if position < 0:
        return 0
    elif position == 0:
        return 1
    elif position in A:
        return 0
    else:
        return (rootCount(position-1)+rootCount(position-2)) % 1000000007
#class

#main function
def main():
    print(rootCount(N))

if __name__ == "__main__":
    main()
