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


def main():
    N, M = map(int, input().split())
    A = [int(input()) for _ in range(M)]

    mod = 10**9 + 7
    dp = [0] * (N + 1)
    dp[0] = 1

    for i in range(1, N + 1):
        if i in A:
            continue

        if i == 1:
            dp[1] = dp[0]
            continue

        dp[i] = dp[i - 1] + dp[i - 2]
        dp[i] %= mod

    print(dp[N])


if __name__ == "__main__":
    main()
