N, M = map(int, input().split())
A = [int(input()) for _ in range(M)]
dp = [0]*(N+1)
dp[0] = 1
for i in range(1,N+1):
    if i in A:
        dp[i] = 0
    else:
        dp[i] = (dp[i-1] + dp[i-2]) % (10**9+7)
print(dp[N])