n,m=map(int,input().split())
a=[int(input()) for i in range(m)]
dp=[0]*(n+1)
dp[0]=1

if 1 in a:
  dp[1]=0
else:
  dp[1]=1

for i in range(1,n):
  if i+1 not in a:
    
    dp[i+1]=(dp[i]+dp[i-1])%(10**9+7)
  else:
    dp[i+1]=0
    
print(dp[n]%(10**9+7))
