Не могу понять
package com.javarush.task.task08.task0828;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.*;
/*
Номер месяца
*/
public class Solution {
public static void main(String[] args) throws IOException {
ArrayList<String> months = new ArrayList<>();
months.add("January");
months.add("February");
months.add("March");
months.add("April");
months.add("May");
months.add("June");
months.add("July");
months.add("August");
months.add("September");
months.add("October");
months.add("November");
months.add("December");
BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
String month = reader.readLine();
int num = 0;
for (int i = 0; i < months.size(); i++) {
if (months.get(i).equals(month)) {
num = i;
}
}
System.out.println(month + " is the " + num + " month");
}
}