import java.util.Stack;

public class Demo{

   public static void main(String[] args){

      String infixExp = "a + b * c + ( d * e + f ) * g";

      System.out.println(infixToPostFix(infixExp));

   }

   public static String infixToPostFix(String infixExp) {
   // provide implementation here
   Stack<String> operators = new Stack<String>();
   String s1 = "";

   String[] split = infixExp.trim().split("\s+");

   for(int i = 0; i < split.length; i++){
      if(split[i].matches("[^()*/%+-]")){
         s1 = s1 + split[i] + " ";
      }else{
         switch(split[i]){
                case "(":
                    operators.push(split[i]);
                    break;
                case ")":
                    while(operators.peek() != "("){ s1 = s1 + operators.pop() + " "; }
                    operators.pop();
                    break;
                case "*":
                case "/":
                case "%":
                    operators.push(split[i]);
                    break;
                case "+":
                case "-":
                    if(!operators.isEmpty()){
                       while(operators.peek() == "*" || operators.peek() == "/" || operators.peek() == "%" ){
                           s1 = s1 + operators.pop() + " ";
                       }
                    }

                    operators.push(split[i]);
                    break;
            }
        }
      }

    return s1;

   }
}