Ragged Right Solution:

import java.util.ArrayList;
import java.util.Scanner;

public class Kattis {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    ArrayList<String> al = new ArrayList<>();
    String temp;
    int longest = 0;
    while(sc.hasNextLine()){
      temp = sc.nextLine();
      longest = temp.length() > longest ? temp.length() : longest;
      al.add(temp);
    }
    int sum = 0;
    for (int i = 0; i < al.size() -1; i++) {
      sum += (longest - al.get(i).length()) * (longest - al.get(i).length());
    }
    System.out.println(sum);
  }
}