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