sal
n,m = map(int,input().split())
a = set([int(input()) for _ in range(m)])
dp = [0]*(n+1)
mod = 10**9+7
dp[0] = 1
dp[1] = int(1 not in a)
for i in range(2,n+1):
  if i in a:
    continue
  dp[i] = (dp[i-1] + dp[i-2])%mod
print(dp[n])
