import java.util.*;
public class Main {
static class Point {
int x, y, moves;
Point(int x, int y, int moves) {
this.x = x;
this.y = y;
this.moves = moves;
}
}
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
int N = sc.nextInt();
int totalCoins = 2 * N;
List<Point> coins = new ArrayList<>();
Set<Point> targets = new HashSet<>();
// Leer las posiciones de las monedas
for (int i = 0; i < totalCoins; i++) {
int x = sc.nextInt();
int y = sc.nextInt();
coins.add(new Point(x, y, 0));
}
// Definir los puntos objetivo
for (int x = 1; x <= N; x++) {
for (int y = 1; y <= 2; y++) {
targets.add(new Point(x, y, 0));
}
}
int totalMoves = 0;
boolean[][] visited = new boolean[2000000001][2000000001];
// Calcular la mínima distancia de cada moneda a un objetivo usando BFS
for (Point coin : coins) {
totalMoves += bfs(coin, targets);
}
System.out.println(totalMoves);
sc.close();
}
private static int bfs(Point start, Set<Point> targets) {
Queue<Point> queue = new LinkedList<>();
Set<String> visited = new HashSet<>();
queue.offer(new Point(start.x, start.y, 0));
visited.add(start.x + "," + start.y);
// Movimientos posibles (arriba, abajo, izquierda, derecha)
int[][] directions = { {0, 1}, {0, -1}, {1, 0}, {-1, 0} };
while (!queue.isEmpty()) {
Point current = queue.poll();
// Verificar si alcanzamos un destino
if (targets.contains(new Point(current.x, current.y, 0))) {
targets.remove(new Point(current.x, current.y, 0)); // Marcar como alcanzado
return current.moves;
}
// Explorar vecinos
for (int[] dir : directions) {
int newX = current.x + dir[0];
int newY = current.y + dir[1];
String key = newX + "," + newY;
if (!visited.contains(key)) {
visited.add(key);
queue.offer(new Point(newX, newY, current.moves + 1));
}
}
}
return Integer.MAX_VALUE; // No debería ocurrir, ya que siempre hay un camino.
}
}
