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

dp = [0]*(N+3)
dp[0] = 1

for i in range(N+1):
    dp[i] = dp[i] % (10**9 + 7)
    if not i+1 in A:
        dp[i+1] += dp[i]
    if not i+2 in A:
        dp[i+2] += dp[i]
print(dp[N])
