N,M = map(int,input().split())
A = list(map(int,[input() for i in range(M)]))

dp = {i:0 for i in A}

dp[0]=1 # 0段目
if 1 in A: # 1段目
  dp[1]=0
else :
  dp[1]=1

for i in range(2,N+1):  
  if i in A:
    continue
  else :
    dp[i]=dp[i-1]+dp[i-2]
print(dp[N]%1000000007)  