N, M = map(int, input().split())
A = [int(input()) for _ in range(M)]
dp = [0] * (N+1)
dp[0] = 1
e = 1e9 + 7
for i in range(1, N+1):
    if i not in A:
        if i == 1:
            dp[i] = 1
            continue
        else:
            dp[i] = (dp[i-1] + dp[i-2]) % e
print(int(dp[N])