from heapq import heappush, heappop, heapify, heapreplace
from collections import defaultdict


class Solution:
    def main(self):
        N, M =map(int, input().split())
        self.memo = {}
        for _ in range(M):
            a = int(input())
            self.memo[a] = 0
        res = self.rec(N)
        print(res)

    def rec(self, n):
        if n < 0:
            return 0
        elif n == 0:
            return 1
        elif n in self.memo:
            return self.memo[n]
        else:
            val = (self.rec(n-1) + self.rec(n-2)) %1000000007
            self.memo[n] = val
            return val


if __name__ == '__main__':
    Solution().main()