How to do assignment 5 on edhesive please help

//To enter a string, and enter a pivot string, and then print in required sequence, the string from pivot string to last as first string, and printed before the left portion of string.

import java.util.Scanner;

public class Main {

 public static void main(String args[]) {

   Scanner s1 = new Scanner(System.in);

   System.out.println("Enter Main String:");

   String f1 = s1.nextLine();

   System.out.println("Enter pivot(string):");

   String piv = s1.nextLine();

   int start1 = f1.indexOf(piv);

   int end1 = piv.length()+start1;

   if (start1 == -1){

     System.out.println("Error: Sub string(Pivot) cannot be found.");

     return;

   }

   String first1 = f1.substring(0,start1-1);

   String second1 = f1.substring(end1);

   if (f1.charAt(start1-1)==' '){

     System.out.println(second1 + " " + piv + " " + first1);

     return;

   }

   System.out.println(second1 + piv + first1);

 }

}

Explanation:

Please check the answer section

because is corrupted like north lol actually it is because they were not school related or they were not related to the question.