Stack_Lab

import java.util.Scanner;
import java.util.Stack;

public class Solution {

    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);

        //System.out.println("Enter the size of the stack: ");
        int size = scan.nextInt();
        scan.nextLine();

        Stack stack = new Stack();

        int countSize = size;
        int maxSoFar = 0;

        while (countSize != 0) {

            //System.out.println("Enter the command: ");
            String str = scan.nextLine();

            int length = str.length();

            String NumCmd = "";

            for (int i = 0; i < length; i++) {
                Character character = str.charAt(i);
                if (Character.isDigit(character)) {
                    NumCmd += character;
                }
            }

            if(NumCmd == "") {
                if (str.equals("PEEK")) {
                    stack.peek();
                    System.out.println(stack.peek());
                }
                if (str.contains("POP")) {
                    stack.pop();
                    System.out.printf("%s ", stack);
                }
            }
            else {
                int x = Integer.parseInt(NumCmd.valueOf(NumCmd));

                if (maxSoFar < x) {
                    maxSoFar = x;
                }

                if (str.contains("PUSH")) {
                    stack.push(x);
                    countSize--;

                }
            }
        }
        System.out.println(maxSoFar);
    }
}

"countSize--" should not be included for POP and PEEK