def main():
    N, M = map(int, input().split())
    A = set()
    for _ in range(M):
        a = int(input())
        A.add(a)
    mod = 10**9 + 7
    dp = [0] * (N+1)
    dp[0] = 1
    if 1 not in A:
        dp[1] = 1
    for i in range(1, N+1):
        if i not in A:
            dp[i] = dp[i-1] + dp[i-2]
            dp[i] %= mod
    return dp[-1]
print(main())
