import sys
input = sys.stdin.readline
n,m = map(int, input().split())
a = [int(input()) for i in range(m)]
mod = (10**9)+7
dp = [1] + [0]*(n)
for i in range(1,n+1):
    if i in a:
        dp[i] == 0
    else:
        dp[i] = dp[i-1] + dp[i-2]
        dp[i] %= mod
print(dp[-1])