Petya has an array aa consisting of nn integers. He wants to remove duplicate (equal) elements.Petya wants to leave only the rightmost entry (occurrence) for each element of the array. The relative order of the remaining unique elements should not be changed.InputThe first line contains a single integer nn (1≤n≤501≤n≤50) — the number of elements in Petya’s array.The following line contains a sequence a1,a2,…,ana1,a2,…,an (1≤ai≤10001≤ai≤1000) — the Petya’s array.OutputIn the first line print integer xx — the number of elements which will be left in Petya’s array after he removed the duplicates.In the second line print xx integers separated with a space — Petya’s array after he removed the duplicates. For each unique element only the rightmost entry should be left.ExamplesinputCopy6
1 5 5 1 6 1
outputCopy3
5 6 1
inputCopy5
2 4 2 4 4
outputCopy2
2 4
inputCopy5
6 6 6 6 6
outputCopy1
6
NoteIn the first example you should remove two integers 11, which are in the positions 11 and 44. Also you should remove the integer 55, which is in the position 22.In the second example you should remove integer 22, which is in the position 11, and two integers 44, which are in the positions 22 and 44.In the third example you should remove four integers 66, which are in the positions 11, 22, 33 and 4

给出n个数，输出有多少个不同的数，并按每个数最后一次出现的顺序输出来

#include <iostream>
#include <cstdio>
#include <algorithm>
#include <cstring>
#include <set>
#include <vector>
using namespace std;
const int N = 10010;
set<int> s;
int a[N];
int main(){
 vector<int> b;
 int n;
 cin >> n;
  for (int i = 1; i <= n; i ++){
  cin >> a[i];
  s.insert(a[i]);
 }
  cout << s.size() << endl;
  multiset<int> y; 
 int cnt = 0;
 for (int i = n; i >= 1; i --){
  y.insert(a[i]);
  if (y.count(a[i]) == 1)
  b.push_back(a[i]);
 }
  for (int i = b.size() - 1; i >= 0; i --)
 if (i != 0)   cout << b[i] << " ";
 else                cout << b[i] << endl;
  return 0;
}