秒

#include<iostream>
#include<set>
using namespace std;
set<int> se_Deduplication;
int main(void){
    int n;
    int cnt=0;
    cin>>n;
    while(n--){
        int x;
        cin>>x;
        se_Deduplication.insert(x);
    }
    set<int>::iterator it_iterations=se_Deduplication.begin();
    for(;it_iterations!=se_Deduplication.end();it_iterations++){
        cnt++;
    }
    cout<<cnt<<"\n";
    it_iterations=se_Deduplication.begin();
    for(;it_iterations!=se_Deduplication.end();it_iterations++){
        cout<<*it_iterations<<" ";
    }
    return 0;
}