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