N, M = map(int, input().split())
a = [int(input()) for _ in range(M)]
a = set(a)
mod = 1000000007
dp = [0]*(N+1)
dp[0] = 1
if a[0] != 1:
    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[N])