#include <iostream>
#include <vector>
#include <string>
#include <algorithm>
#include <map>
#include <set>
#include <queue>
#include <stack>
#include <deque>
#include <cmath>
#include <climits>
#include <cstring>
#include <iomanip>
#include <numeric>
#include <functional>
#include <bitset>
#include <unordered_map>
#include <unordered_set>
#include <chrono>
#include <random>
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
#define rep(a,b) for(int a = 0;a<b;a++)
#define st first
#define nd second
#define pb push_back
#define all(a) a.begin(),a.end()
const int inf = 1e9;
const ll infl = 1e18;
int tab[100007][2];
int main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
int n;
cin >> n;
ll w = 0;
rep(i, 2*n){
ll a, b;
cin >> a >> b;
if(a >= 1 && a <= n){
//cout << "sigma " << a << " " << b << "\n";
if(b == 1 || b == 2){
tab[a-1][b%2]++;
//cout << "sigma " << a << " " << b << "\n";
}
else if(b < 1){
tab[a-1][1]++;
w += -b+1;
}
else{
tab[a-1][0]++;
w += b-2;
}
}
else if(b == 1 || b == 2){
if(a > n){
tab[n-1][(b+1)%2]++;
w += a-n;
}
else{
tab[0][b%2]++;
w += -a+1;
}
}
else{
if(a > n && b > 2){
tab[n-1][0]++;
w += a-n + b-2;
}
else if(a > n && b < 1){
tab[n-1][1]++;
w += a-n - b+1;
}
else if(a < 1 && b > 2){
tab[0][0]++;
w += -a+1 + b-2;
}
else if(a < 1 && b < 1){
tab[0][1]++;
w += -a+1 -b + 1;
}
}
}
rep(i, n-1){
if(tab[i][0] > 0 && tab[i][1] > 0){
w+=tab[i][0]-1;
tab[i+1][0] += tab[i][0]-1;
w+=tab[i][1]-1;
tab[i+1][1] += tab[i][1]-1;
}
else if(tab[i][0] <= 0 && tab[i][1] <= 0){
ll ile = abs(tab[i][0]-1);
tab[i+1][0] -= ile;
w+=ile;
ile = abs(tab[i][1]-1);
tab[i+1][1] -= ile;
w+=ile;
}
else if(tab[i][0] <= 0 && tab[i][1] > 0){
ll ile = min(tab[i][1] - 1, 1 + abs(tab[i][0]));
tab[i][0] += ile;
tab[i][1] -= ile;
w += ile;
if(tab[i][0] <= 0){
tab[i+1][0] -= abs(tab[i][0] - 1);
w += abs(tab[i][0] - 1);
}
if(tab[i][1] > 1){
tab[i+1][1] += tab[i][1] - 1;
w += tab[i][1] - 1;
}
}
else if(tab[i][0] > 0 && tab[i][1] <= 0){
ll ile = min(tab[i][0] - 1, 1 + abs(tab[i][1]));
tab[i][1] += ile;
tab[i][0] -= ile;
w += ile;
if(tab[i][1] <= 0){
tab[i+1][1] -= abs(tab[i][1] - 1);
w += abs(tab[i][1] - 1);
}
if(tab[i][0] > 1){
tab[i+1][0] += tab[i][0] - 1;
w += tab[i][0] - 1;
}
}
}
ll a = tab[n-1][0];
ll b = tab[n-1][1];
if(a < b){
swap(a, b);
}
w += a-1;
cout << w << "\n";
return 0;
}
