 # -*- coding: utf-8 -*-
n, m = map(int, input().split())
a = [int(input()) for _ in range(m)]

INF = 10 ** 9 + 7

dp = [0] * (n+1)
dp[0] = 1

if 1 not in a:
    dp[1] = 1
else:
    dp[1] = 0

for i in range(2, n+1):
    if i in a:
        continue
    dp[i] = dp[i-1] + dp[i-2]
    dp[i] %= INF

print(dp[n])
