#include <stdio.h>
#include <stdlib.h>
#include <string>
#include <iostream>
#include <algorithm>
#include <vector>
#include <set>
#include <memory.h>
#include <map>
#include <math.h>
#include <queue>
#include <stdio.h>
#include <stdlib.h>
#include <string>
#include <iostream>
#include <algorithm>
#include <vector>
#include <set>
#include <memory.h>
#include <map>
#include <math.h>
#include <queue>
#include <stack>
#include <complex>
#include <list>
#include <deque>
#include <pthread.h>
using namespace std;

typedef long long ll;
typedef unsigned long long ull;

#define mp make_pair
#define pb push_back
#define sz(x) (int)x.size()
#define X first
#define Y second
#define all(x) x.begin(),x.end()

class Task
{
    public:
        Task(const int threadsNumber)
        {
            pthread_mutex_init(&mutex,NULL);
        }

        void push(const int value, const int timestamp)
        {
            pthread_mutex_lock(&mutex);
            commands.pb(mp(timestamp, mp(1, value)));
            pthread_mutex_unlock(&mutex);
        }

        void pop(const int timestamp)
        {
            pthread_mutex_lock(&mutex);
            commands.pb(mp(timestamp, mp(0, -1)));
            pthread_mutex_unlock(&mutex);
        }

        void finish()
        {
            freopen("output.txt", "w", stdout);
            vector<int> _stack;
            sort(all(commands));
            for (int i = 0; i < sz(commands); i++)
            {
                if (commands[i].Y.X == 1)
                {
                    _stack.pb(commands[i].Y.Y);
                }
                else
                {
                    printf("%d\n", _stack[sz(_stack)-1]);
                    _stack.pop_back();
                }
            }
        }

        vector< pair< int, pair< int, int> > > commands;
        pthread_mutex_t mutex;
};