N, M = map(int, input().split()) 
a=[int(input()) for _ in range(M)]

dp=[0]*(N+1)
dp[0]=1

for n in range(1,N+1):
	
  if n  in a:
    dp[n]=0
    
  else:
    dp[n]=(dp[n-1]+dp[n-2])%1000000007

print(dp[N])
    