n,m=map(int,input().split())
arr=set([int(input()) for _ in range(m)])
dp=[0]*(n+1)
if 1 not in arr:
  dp[1]=1
if 2 not in arr:
  dp[2]=dp[1]+1
for i in range(3,n+1):
  if i not in arr:
    dp[i]=(dp[i-1]+dp[i-2])%1000000007
print(dp[n]%1000000007)