#include <bits/stdc++.h>
using namespace std;
int main() {
    unordered_map<int,int> mp ;
    vector<int> ans ;
    mp[0] = 1 ;
    mp[1] = 1 ;
    mp[2] = 1 ;
    mp[3] = 1 ;
	cout<<"map size is "<<mp.size()<<endl ;
    for(auto e:mp){
       
        if(e.second == 1)
         { 
             ans.push_back(e.first) ;
             mp.erase(e.first) ;
         }
        else 
           e.second-- ;
    }
    cout<<"map size is "<<mp.size()<<endl ;
    for(int i=0 ; i<ans.size();i++) cout<<ans[i]<<endl ;
    return 0 ;
 }