#include<vector>
#include<iostream>
#include <algorithm>
using namespace std;
bool cmp1_stable(const pair<int,int> &a, const pair<int,int> &b){
    return a.first<b.first;
}
bool cmp2_unstable(const pair<int,int> &a, const pair<int,int> &b)
{
    if(a.first!=b.first)
        return a.first < b.first;
    else
        return a.second > b.second;
}
int main(){

    vector<pair<int,int>> arr = {{4,0},{3,1},{2,2},{2,3},{2,4}};
    sort(arr.begin(),arr.end(),cmp1_stable);//cmp2_unstable
    for(int i=0;i<5;++i){
        cout<<arr[i].first<<" "<<arr[i].second<<endl;
    }

    return 0;
}