Solve the string expression

QUESTION: 

Alphabets are inside () and the number -9<=0>=9 which is under{} solve the string according to the sample input output  

Input (z){-2}oho

Output ZZoho

Input ((X){2}(y){3}(z)){2}

Output xxyyyzxxyyyz

Input ((x){2}){0}

output -(nothing should print)

ANSWER

package Practice;

import java.util.*;

class Expressions {

public static void main(String[] args) {

// TODO Auto-generated method stub

String input,output="",temp="",check="";

Scanner scanner=new Scanner(System.in);

input=scanner.nextLine();

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

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

{

if(input.charAt(i)=='(') {

stack.push("(");

}

else if(input.charAt(i)>='a'&&input.charAt(i)<='z')

{

check+=input.charAt(i);

if(!stack.empty()&&!stack.peek().equals("("))

{

check=stack.pop()+check;

}

stack.push(check);

check="";

}

else if(input.charAt(i)==')')

{

temp=stack.pop();

while(!stack.peek().equals("("))

{

temp=stack.pop()+temp;

}

stack.pop();

stack.push(temp);

}

else if(input.charAt(i)=='{') {

i++;

temp=stack.pop();

if(input.charAt(i)=='-')

{

temp=temp.toUpperCase();

i++;

}

String temp1=temp;

if((input.charAt(i)-48)==0)

temp="";

for(int j=1;j<input.charAt(i)-48;j++)

{

temp+=temp1;

}

i++;

if(input.charAt(i)=='}') {

stack.push(temp);

}

else

{

stack.push("invalid expression");

break;

}

}

}

temp="";

for(int j=0;j<stack.size();j++)

{

temp+=stack.get(j);

}

System.out.println(temp);

}

}