import sys
input = sys.stdin.readline
n,m = map(int,input().split())
hole = []*(n+1)
for i in range(m):
  hole[int(input())] = 1
dp = [0]*(n+1)
MOD = 10**9+7
   
for i in range(1,n+1):
  if hole[i]==1:
    dp[i] = 0
  dp[i] = dp[i-1]+dp[i-2]
  dp[i] %= MOD

print(dp[-1])  
