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

dp = [0]*(n+1)
dp[0] = 1
for i in range(1,n+1):
    dp[i] = (dp[i-1] + dp[i-2]) % (10**9+7)
    if i in a:
        dp[i] = 0
print(dp[n])
