import sys
from collections import deque

def main():
    N, M = map(int, input().split())
    a = deque([int(sys.stdin.readline().strip()) for _ in range(M)])
    atmp = a.popleft()

    dp=[0] * (N+1)
    for i in range(0, N+1):
        if i == atmp:
            if len(a) != 0:
                atmp = a.popleft()
            continue

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

        if dp[i-1] == 0 and dp[i-2] == 0:
            break


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

    print(dp[N] % 1000000007)

if __name__ == '__main__':
    main()