N, M = map(int, input().split())
A = []
for i in range(M):
    a = int(input())
    A.append(a)
mod = 10**9 +7
dp = [0]*(N+1)
dp[0] = 1
if 1 not in A:
    dp[1]=1
for i in range(2, N+1):
    if i not in A:
        dp[i] = (dp[i-1]+dp[i-2])%mod
print(dp[-1])