import sys
input = sys.stdin.readline
n,m = map(int,input().split())
a = [int(input()) for i in range(m)]
dp = [1]*2 + [0 for _ in range(n-1)]
mod = 1000000007
  
for i in range(n-1):
  if i+1 in a:
    dp[i+1] = 0
  dp[i+2] = dp[i]+dp[i+1]
  
  if dp[i+2] >= mod:
    dp[i+2] %= mod

print(dp[-1]%mod)  
