答案

#include <bits/stdc++.h>

using namespace std;

long long n;

int main( ) {
	set<long long> s;
	cin >> n;
	
	for (int i = 1 ; i <= n ; i++ ) {
		long long x;
		cin >> x;
		s.insert(x);
	}
	
	cout << s.size() << endl;
	
	for (auto i : s) cout << i << " ";
    
	
	return 0;
}

#include <iostream>
#include <algorithm>

using namespace std;

long long n;
const long long N = 150;
long long array_[N] , cnt = 0;

//bool comper(long long x , long long y) {
    //return x > y;
//}

int main( ) {
    scanf("%lld" , &n);

    for (int i = 1 ; i <= n ; i++) {
        scanf("%lld" , &array_[i]);
    }

    sort(array_ + 1 , array_ + n + 1);

    //for (int i = 0 ; i <= n ; i++) {
        //cout << a[i] << " ";
    //}
    for (int i = 1 ; i <= n ; i++) {
		if (array_[i] != array_[i - 1]) cnt++;
	}
	
	printf("%lld\n" , cnt);
	
	for (int i = 1 ; i <= n ; i++) {
		if (array_[i] != array_[i - 1]) printf("%lld " , array_[i]);
	}

    return 0;
}