JA-Stacks-Lab-02.SimpleCalculator

import java.util.ArrayDeque;
import java.util.Collections;
import java.util.List;
import java.util.Scanner;


class Main {
  public static void main(String[] args) {

  Scanner sc = new Scanner(System.in);

  ArrayDeque<String> calcStack = new ArrayDeque<>();

   String[] numbers = sc.nextLine().split("\\s+");
   Collections.addAll(calcStack, numbers);

    while(calcStack.size() > 1) {

      int firstNum = Integer.parseInt(calcStack.pop());
      String operator = calcStack.pop();
      int secondNum = Integer.parseInt(calcStack.pop());

        if (operator.equals("+")) {
          calcStack.push(String.valueOf(firstNum + secondNum));
        } else {
          calcStack.push(String.valueOf(firstNum - secondNum));
        }
    }

   System.out.print(calcStack.peek());

  }
}