Java :

import java.util.*;

public class Main{
    public static void main(String args[]){
        Scanner cin=new Scanner(System.in);
        int T=cin.nextInt();
        int a,b,r;
        while(T-->0){
            a=cin.nextInt();
            b=cin.nextInt();
            r=cin.nextInt();
            a+=b;
            if(a==0){
                System.out.println(0);
            }
            else{
                Stack<Integer>stack=new Stack<Integer>();
                while(a!=0){
                    stack.push(a%r);
                    a/=r;
                }
                while(!stack.empty()){
                    System.out.print(stack.peek());
                    stack.pop();
                }
                System.out.println();
            }
       }
    }
}