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

dp = [0]*(n+1)
dp[0] = 1
dp[1] = 1 if (1 not in a) else 0

for i in range(2, n+1):
    if i in a:
        pass
    else:
        dp[i] = dp[i-1] + dp[i-2]
    
print(dp[n]%(10**9+7))