Solve2

package com.company;

import java.io.BufferedReader;
import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.Stack;

public class Solve2 {
    public static void main(String[] args) throws IOException {
        testInput();

        BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
        String problem = in.readLine();
        problem = problem.replaceAll(" ", "");
        problem = problem.replaceAll("[()]", "");

        Stack<Integer> integers = new Stack<>();
        Stack<Character> signs = new Stack<>();

        String number;
        char sign;
        int i = 0;

        boolean isNumber = true;
        for (int j = 0; j < problem.length(); j++) {
            if (!Character.isDigit(problem.charAt(j))) {
                isNumber = false;
                break;
            }
        }

        if (isNumber) {
            System.out.println(problem);
            return;
        }

        while (problem.contains("*") || problem.contains("+") || problem.contains("-")) {
            if (problem.charAt(i) == '*' || problem.charAt(i) == '+' || problem.charAt(i) == '-') {
                number = problem.substring(0, i);
                sign = problem.substring(i, i + 1).charAt(0);
                integers.push(Integer.parseInt(number));
                signs.push(sign);

                problem = problem.substring(i + 1);
                i = 0;
            } else {
                i++;
            }
        }

        long finalSum = Integer.parseInt(problem);
        int rotations = integers.size();

        for (int j = 0; j < rotations; j++) {
            if (signs.peek() == '+') {
                finalSum += integers.pop();
                signs.pop();
            } else if (signs.peek() == '*') {
                finalSum *= integers.pop();
                signs.pop();
            } else if (signs.peek() == '-') {
                finalSum = integers.pop() - finalSum;
                signs.pop();
            }
        }

        System.out.println(finalSum);
    }

    private static void testInput() {
        String test = "546613216894946";
        System.setIn(new ByteArrayInputStream(test.getBytes()));
    }
}