iN=int(raw_input())

iNumS=raw_input()

iNum=[int(n) for n in iNumS.split()]

oNum=[0 for i in range(1001)]

oN=0

for i in range(iN) :

t=iNum[i]

if oNum[t]==0 :

oNum[t]=t

oN+=1

print oN

oNumS=""

for i in range(1001) :

if oNum[i]!=0 :

oNumS=oNumS+str(oNum[i])+" "

print oNumS

看不出缩进怎么办

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