Magic star Intensity code

import java.util.*;

public class Main {

    static class Line {
        int x1, y1, x2, y2;

        public Line(int x1, int y1, int x2, int y2) {
            this.x1 = x1;
            this.y1 = y1;
            this.x2 = x2;
            this.y2 = y2;
        }
    }

    private static int countCells(Line line, Pair<Integer, Integer> star, boolean split) {
        if (line.x1 == line.x2) {
            if (split) {
                return Math.min(Math.abs(star.second - line.y1), Math.abs(star.second - line.y2)) + 1;
            } else {
                return Math.abs(line.y1 - line.y2) + 1;
            }
        } else {
            if (split) {
                return Math.min(Math.abs(star.first - line.x1), Math.abs(star.first - line.x2)) + 1;
            } else {
                return Math.abs(line.x1 - line.x2) + 1;
            }
        }
    }

    private static boolean intersects(Line a, Line b, Pair<Integer, Integer> intersection) {
        if (a.x1 == a.x2 && b.y1 == b.y2) {
            if (b.x1 <= a.x1 && a.x1 <= b.x2 && a.y1 <= b.y1 && b.y1 <= a.y2) {
                intersection.set(a.x1, b.y1);
                return true;
            }
        }
        if (a.y1 == a.y2 && b.x1 == b.x2) {
            if (a.x1 <= b.x1 && b.x1 <= a.x2 && b.y1 <= a.y1 && a.y1 <= b.y2) {
                intersection.set(b.x1, a.y1);
                return true;
            }
        }
        return false;
    }

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        int N = sc.nextInt();
        List<Line> lines = new ArrayList<>();
        for (int i = 0; i < N; ++i) {
            int x1 = sc.nextInt();
            int y1 = sc.nextInt();
            int x2 = sc.nextInt();
            int y2 = sc.nextInt();
            if (x1 > x2 || (x1 == x2 && y1 > y2)) {
                int temp = x1;
                x1 = x2;
                x2 = temp;
                temp = y1;
                y1 = y2;
                y2 = temp;
            }
            lines.add(new Line(x1, y1, x2, y2));
        }

        int K = sc.nextInt();
        Map<Pair<Integer, Integer>, List<Line>> stars = new HashMap<>();

        for (int i = 0; i < N; ++i) {
            for (int j = i + 1; j < N; ++j) {
                Pair<Integer, Integer> intersection = new Pair<>(0, 0);
                if (intersects(lines.get(i), lines.get(j), intersection)) {
                    stars.computeIfAbsent(intersection, k -> new ArrayList<>()).add(lines.get(i));
                    stars.computeIfAbsent(intersection, k -> new ArrayList<>()).add(lines.get(j));
                }
            }
        }

        int totalIntensity = 0;
        for (Map.Entry<Pair<Integer, Integer>, List<Line>> entry : stars.entrySet()) {
            if (entry.getValue().size() / 2 == K) {
                List<Integer> intensities = new ArrayList<>();
                for (Line line : entry.getValue()) {
                    intensities.add(countCells(line, entry.getKey(), true));
                }
                totalIntensity += Collections.min(intensities);
            }
        }

        System.out.println(totalIntensity);
    }

    // Pair class to store x and y coordinates of intersections
    static class Pair<T, U> {
        T first;
        U second;

        public Pair(T first, U second) {
            this.first = first;
            this.second = second;
        }

        public void set(T first, U second) {
            this.first = first;
            this.second = second;
        }
    }
}