stack

import java.awt.List;
import java.util.ArrayList;
import java.util.Scanner;


public class Main {	
	
	public static class Stack
	{
		private int[] mStack;
		final int mMaxCount;
		int mPos;				// 위치이자 개수
		
		public Stack(int size)
		{
			mMaxCount = size;
			mStack = new int[mMaxCount];
			mPos = 0;
		}

		public void push(int value)
		{
			if(mPos >= mMaxCount)
				return;
			
			mStack[mPos] = value;
			++mPos;
		}
		
		public int pop()
		{
			if(0 >= mPos)
			{
				System.out.println("-1");
				return -1;
			}
			
			--mPos;
			int value = mStack[mPos];
			mStack[mPos] = value;
			
			System.out.println(value);
			return value;
		}
		
		public int size()
		{
			System.out.println(mPos);
			return mPos;
		}
		
		public int empty()
		{
			if(0 == mPos)
			{
				System.out.println(1);
				return 1;
			}

			System.out.println(0);
			return 0;
		}
		
		public int top()
		{
			if(0 >= mPos)
			{
				System.out.println(-1);
				return -1;
			}

			System.out.println(mStack[mPos-1]);
			return mStack[mPos-1];
		}
	}
	
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		
		Scanner sc = new Scanner(System.in);
		int count = Integer.parseInt(sc.nextLine());
		Stack stack = new Stack(10000);

		String[] str = new String[count];
		for(int i = 0; i < count; ++i)
		{
			str[i] = sc.nextLine();
		}
		
		for(int i = 0; i < count; ++i)
		{
			Parser(stack, str[i]);
		}

	}
	
	static void Parser(Stack stack, String str)
	{
		String command = str;
		int spaceIndex = str.lastIndexOf(" ");
		if(-1 != spaceIndex)
		{
			command = str.substring(0, spaceIndex);		
		}
		
		// 비어있는문자가 없다면 하나의 문자로 이루어진 것
		if(command.equals(""))
		{
			System.out.println("equals");
			command = str;
		}
		
		if(command.equals("push"))
		{
			int tempSpaceIndex = str.lastIndexOf(" ");
			if(-1 == tempSpaceIndex)
			{
				System.out.println("value를 입력하세요");
				return;
			}
			
			String temp = str.substring(tempSpaceIndex+1, str.length());			
			int value = Integer.parseInt(temp);
			stack.push(value);
		}
		else if(command.equals("pop"))
		{
			stack.pop();
		}
		else if(command.equals("size"))
		{
			stack.size();			
		}
		else if(command.equals("empty"))
		{
			stack.empty();
		}
		else if(command.equals("top"))
		{
			stack.top();
		}
	}
}