import java.util.*;
import static java.lang.Math.*;
public class joi2019_ho_t4 {
static int clamp(int value, int min, int max) {
if (value < min) return min;
if (value > max) return max;
return value;
}
static long adjustmentCost(int c, int r, int maxCol) {
long cost = 0;
if (r < 1) cost += (1 - r);
if (r > 2) cost += (r - 2);
if (c < 1) cost += (1 - c);
if (c > maxCol) cost += (c - maxCol);
return cost;
}
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
int n = sc.nextInt();
int totalCoins = 2 * n;
int[] coinsRow1 = new int[n + 1];
int[] coinsRow2 = new int[n + 1];
long clampCost = 0;
for (int i = 0; i < totalCoins; i++) {
int c = sc.nextInt();
int r = sc.nextInt();
clampCost += adjustmentCost(c, r, n);
int validC = clamp(c, 1, n);
int validR = clamp(r, 1, 2);
if (validR == 1)
coinsRow1[validC]++;
else
coinsRow2[validC]++;
}
int[] X = new int[n + 1];
int[] Y = new int[n + 1];
for (int i = 1; i <= n; i++) {
X[i] = coinsRow1[i] - 1;
Y[i] = coinsRow2[i] - 1;
}
int[] S1 = new int[n + 1];
int[] S2 = new int[n + 1];
S1[0] = 0; S2[0] = 0;
for (int i = 1; i <= n; i++) {
S1[i] = S1[i - 1] + X[i];
S2[i] = S2[i - 1] + Y[i];
}
int deltaMin = -100, deltaMax = 100;
List<Map<Integer, Long>> dp = new ArrayList<>();
for (int i = 0; i <= n; i++) {
dp.add(new HashMap<>());
}
for (int d = deltaMin; d <= deltaMax; d++) {
long cost = abs(S1[1] - d) + abs(S2[1] + d) + abs(d);
dp.get(1).put(d, cost);
}
for (int i = 2; i <= n - 1; i++) {
Map<Integer, Long> prev = dp.get(i - 1);
Map<Integer, Long> cur = dp.get(i);
for (int dPrev = deltaMin; dPrev <= deltaMax; dPrev++) {
if (!prev.containsKey(dPrev)) continue;
long prevCost = prev.get(dPrev);
for (int d = deltaMin; d <= deltaMax; d++) {
long horiz = abs(d - dPrev);
long balance = abs(S1[i] - d) + abs(S2[i] + d);
long candidate = prevCost + horiz + balance;
if (!cur.containsKey(d) || candidate < cur.get(d)) {
cur.put(d, candidate);
}
}
}
}
long finalCost = Long.MAX_VALUE;
Map<Integer, Long> prev = dp.get(n - 1);
for (int dPrev = deltaMin; dPrev <= deltaMax; dPrev++) {
if (!prev.containsKey(dPrev)) continue;
long candidate = prev.get(dPrev) + abs(S1[n] - dPrev);
finalCost = min(finalCost, candidate);
}
long answer = clampCost + finalCost;
System.out.println(answer);
}
}
