#39929: C++ 給自己的解答
mu0975353917@gmail.com
(Moon Chan)
#include <bits/stdc++.h>
using namespace std;
vector <int> v[10005];
int a[10005];
queue <int> q;
int main() {
int a,s;
cin>>a;
set<int> b;
for(int i=0;i<a;i++)
{
cin>>s;
b.insert(s);
}
cout<<b.size()<<endl;
for(auto &s:b)
{
cout<<s<<" ";
}
cout<<endl;
}