import java.time.LocalDate;
import java.time.format.DateTimeFormatter;
import java.time.format.DateTimeFormatterBuilder;
import java.time.temporal.ChronoField;

import static java.time.temporal.ChronoUnit.WEEKS;

public class Main {
    public static void main(String[] args) {
        String strWeekA = "2012-W48";
        String strWeekB = "2013-W03";

        DateTimeFormatter dtf = new DateTimeFormatterBuilder()
                .appendPattern("YYYY-'W'ww")
                .parseDefaulting(ChronoField.DAY_OF_WEEK, 1)
                .toFormatter();

        LocalDate date1 = LocalDate.parse(strWeekA, dtf);
        LocalDate date2 = LocalDate.parse(strWeekB, dtf);

        System.out.println(WEEKS.between(date1, date2));
    }
}