n=int(input()) arr=[] d={} for x in map(int,input().split()): if x not in d : arr.append(x) d[x]=1 l=len(arr) for i in range (l-1): for j in range (i+1,l): if arr[i]>arr[j]: t=arr[i] arr[i]=arr[j] arr[j]=t print(l) for i in range (l): if i==l-1: print(arr[i]) else: print(arr[i],end=" ")