# -*- coding: utf-8 -*-

n, m = map(int, input().split())
a = [int(input()) for _ in range(m)]

mod = 10**9+7

dp = [0] * (n+1)
dp[0] = 1
if 1 in a:
    dp[1] = 0
else:
    dp[1] = 1

for i in range(2, n+1):
    if i not in a:
        temp = dp[i-1] + dp[i-2]
        dp[i] = temp%mod
    else:
        dp[i] = 0

#print(dp)
print(dp[-1])
