#include <iostream>
#include <cstdio>
#include <string>
#include <vector>
#include <algorithm>
#include <windows.h>
using namespace std;

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

struct node {
	int value;
	node * prev;
	node() {
		value = 0;
		prev = NULL;
	}
};

struct stack{
	node *last;
	int siz;
	stack() {
		last = (node*)malloc(sizeof(last));
		last->prev = NULL;
		last->value = 0;
		siz = 0;
	}

	void push(int n) {
		node *t = (node*)malloc(sizeof(last));
		if(siz == 0 ) {
			last -> value = n;
		} else {
			t -> prev = last;
			t -> value = n;
			last = t;
		}
		siz++;
	}

	void pop() {
		if(siz > 0) {
			node *t = last;
			last = last -> prev;
			free(t);
		}
siz--;
	}

	int top() {
		if(siz > 0) {
			return last -> value;
		}
	}

	int size() {
		return siz;
	}

	void clear() {
		while(siz > 0) {
			node *t = last;
			last = last -> prev;
			free(t);
			siz--;
		}
	}
};

int main() {
	stack a;
	for(int  i = 0; i < 1000000; i++) {
		a.push(i);
		//cout << a.top() << endl;
	}
	//Sleep(1000);
	puts("OK");
	a.clear();
	return 0;
}