import java.util.ArrayList;
import java.util.Arrays;
import java.util.Comparator;
import java.util.HashSet;
import java.util.LinkedList;
import java.util.List;
import java.util.Queue;
import java.util.Scanner;
import java.util.Set;
class Coin {
static class Position {
int x, y, moves;
Position(int x, int y, int moves) {
this.x = x;
this.y = y;
this.moves = moves;
}
}
public static int minMovesToTarget(int N, int[][] coins) {
List<Position> targets = new ArrayList<>();
for (int x = 1; x <= N; x++) {
targets.add(new Position(x, 1, 0));
targets.add(new Position(x, 2, 0));
}
Arrays.sort(coins, Comparator.comparingInt(a -> a[0]));
targets.sort(Comparator.comparingInt(a -> a.x));
boolean[] usedTarget = new boolean[2 * N];
int totalMoves = 0;
for (int i = 0; i < 2 * N; i++) {
int minDist = Integer.MAX_VALUE;
int bestTarget = -1;
for (int j = 0; j < targets.size(); j++) {
if (!usedTarget[j]) {
int dist = bfs(coins[i][0], coins[i][1], targets.get(j).x, targets.get(j).y);
if (dist < minDist) {
minDist = dist;
bestTarget = j;
}
}
}
if (bestTarget != -1) {
usedTarget[bestTarget] = true;
totalMoves += minDist;
}
}
return totalMoves;
}
private static int bfs(int startX, int startY, int targetX, int targetY) {
if (startX == targetX && startY == targetY) return 0;
Queue<Position> queue = new LinkedList<>();
Set<String> visited = new HashSet<>();
queue.add(new Position(startX, startY, 0));
visited.add(startX + "," + startY);
int[][] directions = {{0, 1}, {0, -1}, {1, 0}, {-1, 0}};
while (!queue.isEmpty()) {
Position current = queue.poll();
for (int[] dir : directions) {
int newX = current.x + dir[0];
int newY = current.y + dir[1];
if (newX == targetX && newY == targetY) {
return current.moves + 1;
}
String newState = newX + "," + newY;
if (!visited.contains(newState)) {
visited.add(newState);
queue.add(new Position(newX, newY, current.moves + 1));
}
}
}
return Integer.MAX_VALUE;
}
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
int N = scanner.nextInt();
int[][] coins = new int[2 * N][2];
for (int i = 0; i < 2 * N; i++) {
coins[i][0] = scanner.nextInt();
coins[i][1] = scanner.nextInt();
}
System.out.println(minMovesToTarget(N, coins));
scanner.close();
}
}
