import java.util.*;
public class joi2019_ho_t4 {
static class Coin implements Comparable<Coin> {
long x, y;
Coin(long x, long y) {
this.x = x; this.y = y;
}
public int compareTo(Coin o) {
return Long.compare(this.x, o.x);
}
}
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
int n = sc.nextInt();
int total = 2 * n;
Coin[] coins = new Coin[total];
long extraCost = 0;
for (int i = 0; i < total; i++) {
long cx = sc.nextLong(), cy = sc.nextLong();
if(cx < 1) { extraCost += (1 - cx); cx = 1; }
if(cx > n) { extraCost += (cx - n); cx = n; }
if(cy < 1) { extraCost += (1 - cy); cy = 1; }
if(cy > 2) { extraCost += (cy - 2); cy = 2; }
coins[i] = new Coin(cx, cy);
}
Arrays.sort(coins);
long costX = 0;
for (int i = 0; i < total; i++) {
long target = (i / 2) + 1;
costX += Math.abs(coins[i].x - target);
}
long INF = Long.MAX_VALUE / 2;
long[] dp = new long[n + 1];
Arrays.fill(dp, INF);
dp[0] = 0;
for (int i = 0; i < total; i++) {
long costRow1 = (coins[i].y == 1 ? 0 : 1);
long costRow2 = (coins[i].y == 2 ? 0 : 1);
long[] newdp = new long[n + 1];
Arrays.fill(newdp, INF);
for (int j = 0; j <= n; j++) {
if (dp[j] < INF) {
// Asignar a fila 2 (no incrementa el contador de fila1)
newdp[j] = Math.min(newdp[j], dp[j] + costRow2);
// Asignar a fila 1 (incrementa contador)
if(j + 1 <= n)
newdp[j + 1] = Math.min(newdp[j + 1], dp[j] + costRow1);
}
}
dp = newdp;
}
long costY = dp[n];
System.out.println(extraCost + costX + costY);
sc.close();
}
}
