N,M=map(int,input().split())
a=[int(input()) for _ in range(M)]
dp=[1]*(N+1)
if 1 in a:
  dp[1]=0
else:
  dp[1]=1
for i in range(1,N+1):
  if i in a:
    dp[i]=0
  else:
    dp[i]=dp[i-1]+dp[i-2]
  dp[i]%=1000000007
print(dp[N])


