package stack_and_queue;

import java.util.Stack;

import java.util.*;

public class Infix_To_Postfix {

static int Prec(char ch){

switch(ch){

case '+':

case '-':

return 1;

case '*':

case '/':

return 2;

case '^':

return 3;

}

return -1;

}

static String infixToPostfix(String exp){

StringBuilder result = new StringBuilder(new String(" "));

Stack<Character> stack = new Stack<>();

for(int i = 0 ; i < exp.length() ; ++i){

char c = exp.charAt(i);

if(Character.isLetterOrDigit(c))

result.append(c);

else if(c == '(')

stack.push(c);

else if (c == ')'){

while (!stack.isEmpty() && stack.peek() != '(')

result.append(stack.pop());

stack.pop();

}

else{

while(!stack.isEmpty() && Prec(c) <= Prec(stack.peek()))

result.append(stack.pop());

}

stack.push(c);

}

while (!stack.isEmpty()) {

if(stack.peek() == '(')

return "Invalid Expression";

result.append(stack.pop());

}

return result.toString();

}

public static void main(String[] args) {

Scanner sc = new Scanner(System.in);

String exp = sc.nextLine();

System.out.println(infixToPostfix(exp));

sc.close();

}

}