import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.IOException;
import java.util.StringTokenizer;
 
public class Main {
 
	public static int[] stack;
	public static int size = 0;
 
 
	public static void main(String[] args) throws IOException {
 
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		StringBuilder sb = new StringBuilder();
		
		
		StringTokenizer st;
		
		int N = Integer.parseInt(br.readLine());
 
		stack = new int[N];
		
		while (N-- > 0) {
			st = new StringTokenizer(br.readLine(), " ");
 
			switch (st.nextToken()) {
			
			case "push":
				push(Integer.parseInt(st.nextToken()));
				break;
				
			case "pop":
				sb.append(pop()).append('\n');
				break;
				
			case "size":
				sb.append(size()).append('\n');
				break;
				
			case "empty":
				sb.append(empty()).append('\n');
				break;
				
			case "top":
				sb.append(top()).append('\n');
				break;
			}
 
		}
		System.out.println(sb);
	}
 
	public static void push(int item) {
		stack[size] = item;
		size++;
	}
	
	public static int pop() {
		if(size == 0) {
			return -1;
		}
		else {
			int res = stack[size - 1];
			stack[size - 1] = 0;
			size--;
			return res;
		}
	}
	
	public static int size() {
		return size;
	}
	
	public static int empty() {
		if(size == 0) {
			return 1;
		}
		else {
			return 0;
		}
	}
	
	public static int top() {
		if(size == 0) {
			return -1;
		}
		else {
			return stack[size - 1];
		}
	}
	
}

class Solution {
    public boolean isValid(String s) {
        
        if(s.length() % 2 == 1)
        return false;
     
        Stack<Character> stack = new Stack<Character>();
        for(int i = 0; i < s.length(); i++){
            if(s.charAt(i) == '(')
            {
                stack.push(')');
            }
            else if(s.charAt(i) == '{')
            {
                stack.push('}');
            }
            else if(s.charAt(i) == '[')
            {
                stack.push(']');
            }
            else if(stack.isEmpty() || stack.pop() != s.charAt(i))
                return false;
         }
         return stack.isEmpty();
    }
}

class Solution {
    public List<Integer> topKFrequent(int[] nums, int k) {
        Map<Integer, Integer> map = new HashMap<>();
        for(int num : nums){ map.put(num, map.getOrDefault(num, 0) + 1); }
        
        Queue<Integer> heap = new PriorityQueue<>((a, b) -> map.get(b) - map.get(a));
        for(int key : map.keySet()){ heap.add(key); }
        
        List<Integer> ans = new ArrayList<>();
        for(int i = 0; i < k; i++){
            ans.add(heap.poll());
        }
        
        return ans;
    }
}

class Solution {
    public int[] plusOne(int[] digits) {
        //제일 끝에 1 더하기
        //9일경우 주의하기
        
        for (int i = digits.length - 1; i >=0; i--) {
            if (digits[i] != 9) {
                digits[i]++;
                break;
            } else {
                digits[i] = 0;
            }
        }
        if (digits[0] == 0) {
            int[] res = new int[digits.length+1];
            res[0] = 1;
            return res;
        }
        return digits;

        }
}

class Solution {
    public int lengthOfLastWord(String s) {
        int lenIndex = s.length()-1;
        int len = 0;
        
        //마지막 단어 찾기
        for (int i=lenIndex; i>=0 && s.charAt(i)==' '; i--) 
            lenIndex--;
        //카운트하기
        for (int i=lenIndex; i>=0 && s.charAt(i)!=' '; i--) 
            len++;
        return len;
        
        }
}

class Solution {
    public int strStr(String haystack, String needle) {
        if(needle =="" || haystack ==""){
            return 0;
        }

        int l1 = haystack.length(), l2 = needle.length();
        if (l1 < l2) {
            return -1;
        } 
        int threshold = l1 - l2;
        for (int i = 0; i <= threshold; ++i) {
            if (haystack.substring(i,i+l2).equals(needle)) {
                return i;
            }
        }
        return -1;
    }
        
    
}

class Solution {
    public int[] twoSum(int[] nums, int target) {
        int first = nums[0];
        for (int i=0; i<nums.length-1; i++){
            for (int j=i+1; j<nums.length; j++){
                if(nums[i]+nums[j] == target){
                    return new int[]{i,j};
                }
            }
        }
        return new int[2];
    }
}