#include <bits/stdc++.h>
using namespace std;
#define int long long
#define double long double
#define FOR(i, l, r, d) for(int i=(l); i<=(r); i+=(d))
#define szof(x) ((int)(x).size())
#define vi vector<int>
#define pii pair<int, int>
#define F first
#define S second
#define pb push_back
#define eb emplace_back
#define mkp make_pair
const int INF = INT_MAX;
const int LNF = INF*INF;
const int MOD = 1000000007;
const int mod = 998244353;
const double eps = 1e-12;
//#pragma GCC optimize("Ofast")
//#pragma GCC optimize("unroll-loops")
const int MAX = 100010;
int n;
int cnt[3][MAX];
int res;
signed main(){
ios_base::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
cin>>n;
FOR(i, 1, 2, 1){
FOR(j, 1, n, 1){
cnt[i][j]--;
}
}
FOR(i, 1, 2*n, 1){
int x, y;
cin>>x>>y;
if(x < 1){
res += 1-x;
x = 1;
}
if(x > n){
res += x-n;
x = n;
}
if(y < 1){
res += 1-y;
y = 1;
}
if(y > 2){
res += y-2;
y = 2;
}
cnt[y][x]++;
}
FOR(i, 1, n, 1){
int d;
if(cnt[1][i] > 0 and cnt[2][i] < 0){
d = min(cnt[1][i], -cnt[2][i]);
cnt[1][i] -= d;
cnt[2][i] += d;
res += d;
}
if(cnt[1][i] < 0 and cnt[2][i] > 0){
d = min(-cnt[1][i], cnt[2][i]);
cnt[1][i] += d;
cnt[2][i] -= d;
res += d;
}
cnt[1][i+1] += cnt[1][i];
cnt[2][i+1] += cnt[2][i];
res += abs(cnt[1][i]) + abs(cnt[2][i]);
cnt[1][i] = 0;
cnt[2][i] = 0;
}
cout<<res<<'\n';
return 0;
}
