def resolve():


    import sys
    input = sys.stdin.readline
    n, m = map(int, input().split())
    dp = [0] * (n + 2)

    li_broken = [0] * m
    for i in range(m):
        li_broken[i] = int(input())

    dp[n] = 1
    li_i = list(reversed(range(n)))

    for i in li_i:

        if i in li_broken:
            dp[i] = 0

        else:
            dp[i] = (dp[i+1] + dp[i+2]) % 1000000007

    print(dp[0])
    
resolve()