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

mod = 10**9+7

dp = [0]*(n+5)
dp[0] = 1
dp[1] = 1

for a in A:
    dp[a] = -1
for i in range(2,n+1):
    if dp[i] == 0:
        dp[i] = max(0,dp[i-1])%mod+max(0,dp[i-2])%mod

print(max(dp[n],0))