Python

a=int(input())
b=list(map(int,input().split(" ")))
c=[0]*1000
d=0
for i in range(0,a):
    if c[b[i]]==0:
        d+=1
        c[b[i]]=b[i]
print(d)
for i in range(len(c)):
    if c[i]!=0:
        print(c[i],end=" ")