n,m=map(int,input().split())
a=[int(input()) for i in range(m)]
dp=[0]*(n+1)
dp[0]=0
if 1 in a:
  dp[1]=0
  dp[2]=1
else:
  dp[1]=1
  dp[2]=2
for i in range(3,n+1):
  if i in a:
    dp[i]=0
  else:
    dp[i]=dp[i-1]+dp[i-2]
print(dp[n]%1000000007)