[Gold 3] 1918번 후위 표기식

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

public class Main {
    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        String s = br.readLine();
        StringBuilder sb = new StringBuilder();
        Stack<Character> stack = new Stack<>();
        
        for(int i=0; i<s.length(); i++) {
            char c = s.charAt(i);
            
            switch(c) {
                case '+':
                case '-':
                case '*':
                case '/':
                    while(!stack.isEmpty() && priority(c)<=priority(stack.peek())) {
                        sb.append(String.valueOf(stack.pop()));
                    }
                    
                    stack.push(c);
                    break;
                case '(':
                    stack.push(c);
                    break;
                case ')':
                    while(stack.peek()!='(') { sb.append(String.valueOf(stack.pop())); }
                    
                    stack.pop();
                    break;
                default:
                    sb.append(String.valueOf(c));
            }
        }
        
        while(!stack.isEmpty()) { sb.append(String.valueOf(stack.pop())); }
        
        System.out.println(sb);
    }
    
    public static int priority(char c) {
        if(c=='(') { return 1; }
        else if(c=='+' || c=='-') { return 2; }
        else { return 3; }
    }
}