import sys
n,m = map(int,input().split())
ls = [int(input()) for _ in range(m)]
dp = [0]*(n+1)
dp[0] = 1
for i in range(1,n+1):
    if i not in ls:
        dp[i] = (dp[i-1]+dp[i-2])
        if dp[i] >= 10**9+7:
            dp[i] %= 10**9+7 
    else:
        if i-1 in ls:
            print(0)
            sys.exit()
print(dp[-1])