#include <bits/stdc++.h>
using namespace std;
#define pb push_back
#define st first
#define nd second
typedef long long ll;
typedef long double ld;
const ll I = 1'000'000'000'000'000'000LL;
const int II = 2'000'000'000;
const ll M = 1'000'000'007LL;
const int N = 1<<18;
pair<int, int> co[N];
vector<int> pos[2];
int tab[N];
map<pair<int, int>, ll> dis;
map<pair<int, int>, ll>::iterator it;
ll A(int a, int b)
{
if(a > b) return a - b;
return b - a;
}
ll Dijsktra()
{
priority_queue<pair<ll, pair<int, int> >> q;
int n = pos[0].size(), m = pos[1].size();
dis[make_pair(0, 0)] = 0;
q.push(make_pair(0, make_pair(0, 0)));
while((int)q.size() > 0)
{
int a = q.top().nd.st, b = q.top().nd.nd;
ll d = -q.top().st, o;
q.pop();
int p = (a + b) / 2 + 1;
if(dis[make_pair(a, b)] != d) continue;
// cout << "\nD: " << a << " " << b << " " << d << "\n";
if(a == n && b == m) return d;
if(a < n && b < m)
{
o = d + A(pos[0][a], p) + A(p, pos[1][b]);
if(dis.find(make_pair(a + 1, b + 1)) == dis.end()) dis[make_pair(a + 1, b + 1)] = I;
it = dis.find(make_pair(a + 1, b + 1));
if((*it).nd > o)
{
// cout << "E: " << a + 1 << " " << b + 1 << " " << o << "\n";
(*it).nd = o;
q.push(make_pair(-o, make_pair(a + 1, b + 1)));
}
}
if(a < n - 1)
{
o = d + A(pos[0][a], p) + A(pos[0][a + 1], p) + 1LL;
if(dis.find(make_pair(a + 2, b)) == dis.end()) dis[make_pair(a + 2, b)] = I;
it = dis.find(make_pair(a + 2, b));
if((*it).nd > o)
{
// cout << "E: " << a + 2 << " " << b << " " << o << "\n";
(*it).nd = o;
q.push(make_pair(-o, make_pair(a + 2, b)));
}
}
if(b < m - 1)
{
o = d + A(pos[1][b], p) + A(pos[1][b + 1], p) + 1LL;
if(dis.find(make_pair(a, b + 2)) == dis.end()) dis[make_pair(a, b + 2)] = I;
it = dis.find(make_pair(a, b + 2));
if((*it).nd > o)
{
// cout << "E: " << a << " " << b + 2 << " " << o << "\n";
(*it).nd = o;
q.push(make_pair(-o, make_pair(a, b + 2)));
}
}
}
return -1LL;
}
void Solve()
{
int n;
ll answer = 0LL;
cin >> n;
for(int i = 1; i <= 2 * n; ++i)
{
cin >> co[i].st >> co[i].nd;
if(co[i].st < 1)
{answer += 1 - co[i].st; co[i].st = 1;}
if(co[i].st > n)
{answer += co[i].st - n; co[i].st = n;}
if(co[i].nd < 1)
{answer += 1 - co[i].nd; co[i].nd = 1;}
if(co[i].nd > 2)
{answer += co[i].nd - 2; co[i].nd = 2;}
// cout << "I: " << co[i].st << " " << co[i].nd << "\n";
pos[co[i].nd - 1].pb(co[i].st);
}
sort(pos[0].begin(), pos[0].end());
sort(pos[1].begin(), pos[1].end());
ll ans = Dijsktra();
ans += answer;
cout << ans << "\n";
}
int main()
{
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
//int t; cin >> t;
//while(t--)
Solve();
return 0;
}
