Объясните пожалуйста почему :)
package com.javarush.task.task04.task0419;
import java.io.BufferedReader;
import java.io.InputStreamReader;
public class Solution {
public static void main(String[] args) throws Exception {
BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
int a = Integer.parseInt(reader.readLine());
int b = Integer.parseInt(reader.readLine());
int c = Integer.parseInt(reader.readLine());
int d = Integer.parseInt(reader.readLine());
if (a == b && a == c && a == d)
System.out.println(a);
else if (a > b && a > c && a > d)
System.out.println(a);
else if (b > a && b > c && b > d)
System.out.println(b);
else if (c > a && c > b && c > d)
System.out.println(c);
else if (d > a && d > b && d > c)
System.out.println(d);
}
}