JAVA STACK .......EMPTY STACK EXCEPTION......

Question

/*

1 x -Push the element x into the stack.
2 -Delete the element present at the top of the stack.
3 -Print the maximum element in the stack.

The first line of input contains an integer,N . The next N lines each contain an above mentioned query. (It is guaranteed that each query is valid.) */

import java.io.*;
import java.util.*;

public class stack {

static void Sta_push( Stack <Integer> stack, Stack <Integer> stack2,int x)
{
if (stack.isEmpty()) { // if stack is empty, insert the number in both
// stacks
stack.add(x);
stack2.add(x); }
else {
// check if number in Stack(track) is bigger than x
// which ever is bigger, insert it into Stack

int a = stack2.peek();
stack2.add(Math.max(a, x));
stack.add(x); // insert it into main stack.
}

}
static int getMax(Stack <Integer> stack2)
{ return( (Integer)stack2.peek()); }

static void Sta_pop(Stack<Integer> stack, Stack<Integer> stack2)
{
if (!stack.isEmpty())
{ stack.pop();
stack2.pop();
}
}

public static void main(String[] args) {

Stack<Integer> stack = new Stack<Integer>();
Stack<Integer> stack2 = new Stack<Integer>();

Scanner sc= new Scanner(System.in);
int N= sc. nextInt();

for(int i= 1;i<=N;i++)
{
int q= sc.nextInt();

//System.out.println(q);
//System.out.println(r);
if(q==1)
{ int r = sc.nextInt();
Sta_push(stack, stack2,r); }

if(q==2);
Sta_pop(stack , stack2);

if(q==3)
{ int c= getMax(stack2);
System.out.println(c); }

}}

Answer 1

Not sure what you're asking but

if (!stack.isEmpty()) {
stack.pop();
stack2.pop();
}

is this causing your error?
You're popping off stack2 while only checking stack1