N, M = map(int, input().split())
A = list(int(input()) for _ in range(M))
P = 10**9 + 7

dp = [0] * (N+1)
dp[0] = 1
dp[1] = 1 if 1 not in A else 0
for i in range(2, N+1):
    if i not in A:
        dp[i] = (dp[i-1] + dp[i-2]) % P
    else:
        dp[i] = 0
print(dp[N])