N, M = map(int, input().split())
A = set(list(int(input()) for _ in range(M)))



dp = [0]* (N+1)
dp[0] = 1

for i in range(1, N+1):
    dp[i] = (dp[i-1] + dp[i-2])%(10**9+7)
    if i in A:
        dp[i] = 0
print(dp[-1])
