easy

def delete_dumplis(arr):
    arr1=[]
    for i in arr:
        if i not in arr1:
            arr1.append(i)
    return arr1
n=int(input())
l=list(map(int,input().split()))
print(len(sorted(delete_dumplis(l))))
print(' '.join(map(str,sorted(delete_dumplis(l)))))