N, M = [int(_) for _ in input().split()]
A = [int(input()) for _ in range(M)]

dp = [0 for _ in range(N+1)]
P = 10**9 + 7

dp[0] = 1
for i in range(1, N+1):
    if i in A:
        dp[i] = 0
    elif i == 1:
        dp[i] = dp[i-1] % P
    else:
        dp[i] = (dp[i-1] + dp[i-2]) % P
print(dp[-1])
