//çalışan kazanır//
#include "bits/stdc++.h"
using namespace std;
#define int long long
#define pb push_back
#define S second
#define F first
#define all(x) x.begin(),x.end()
#define YOSIK() ios_base::sync_with_stdio(0),cin.tie(0)
int gcd (int a, int b) {if (b == 0){return a;}else {return gcd (b, a % b);}}
const int N = 4e5 + 15;
const int INF = 1e18;
const int MOD = 1e9 + 7;
const int MODD = 1070234587ll;
const double eps = 0.0001;
const int p = 87;
int n, x[N], y[N];
int cnt[N][3], dp[2001][2001];
void solution () {
cin >> n;
for (int i = 1; i <= n * 2; ++ i) cin >> x[i] >> y[i];
int res = 0;
for (int i = 1; i <= n * 2; ++ i) {
if (1 <= x[i] && x[i] <= n) {
if (1 <= y[i] && y[i] <= 2) cnt[x[i]][y[i]] ++;
if (y[i] < 1) cnt[x[i]][1] ++, res += (1 - y[i]), y[i] = 1;
if (2 < y[i]) cnt[x[i]][2] ++, res += (y[i] - 2), y[i] = 2;
}
if (x[i] < 1) {
res += 1 - x[i];
if (1 <= y[i] && y[i] <= 2) cnt[1][y[i]] ++;
if (y[i] < 1) cnt[1][1] ++, res += (1 - y[i]), y[i] = 1;
if (2 < y[i]) cnt[1][2] ++, res += (y[i] - 2), y[i] = 2;
x[i] = 1;
}
if (n < x[i]) {
res += x[i] - n;
if (1 <= y[i] && y[i] <= 2) cnt[n][y[i]] ++;
if (y[i] < 1) cnt[n][1] ++, res += (1 - y[i]), y[i] = 1;
if (2 < y[i]) cnt[n][2] ++, res += (y[i] - 2), y[i] = 2;
x[i] = n;
}
}
n *= 2;
vector <pair <int, int>> ord;
for (int i = 1; i <= n; ++ i) ord.pb ({x[i], y[i]});
sort (all (ord));
for (int i = 0; i <= n / 2; ++ i) {
for (int j = 0; j <= n / 2; ++ j) {
if (!i && !j) continue;
else if (!i) dp[i][j] = dp[i][j - 1] + abs(ord[i + j - 1].F - j) + (ord[i + j - 1].S == 1);
else if (!j) dp[i][j] = dp[i - 1][j] + abs(ord[i + j - 1].F - i) + (ord[i + j - 1].S == 2);
else {
dp[i][j] = dp[i][j - 1] + abs(ord[i + j - 1].F - j) + (ord[i + j - 1].S == 1);
dp[i][j] = min (dp[i][j], dp[i - 1][j] + abs(ord[i + j - 1].F - i) + (ord[i + j - 1].S == 2));
}
}
}
cout << dp[n/2][n/2] + res;
return;
}
signed main() {
// YOSIK();
// srand (time(0));
// freopen ("E.in", "r", stdin);
// freopen ("E.out", "w", stdout);
int TT = 1;// cin >> TT;
for (int i = 1; i <= TT; ++ i) {
// cout << "Case " << i << ": ";
solution ();
}
return 0;
}
