#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<ll, ll> pll;
class Solution {
private:
vector<pll> getNeighbors(pll pos) {
vector<pll> neighbors = {
{pos.first + 1, pos.second},
{pos.first - 1, pos.second},
{pos.first, pos.second + 1},
{pos.first, pos.second - 1}
};
return neighbors;
}
ll bfs(pll start, pll end) {
if (start == end) return 0;
set<pll> visited;
queue<pair<pll, ll>> q;
visited.insert(start);
q.push({start, 0});
while (!q.empty()) {
auto [pos, dist] = q.front();
q.pop();
if (pos == end) {
return dist;
}
for (auto next : getNeighbors(pos)) {
if (visited.find(next) == visited.end()) {
visited.insert(next);
q.push({next, dist + 1});
}
}
}
return LLONG_MAX;
}
public:
ll getMinimumOperations(ll N, vector<pll>& coins) {
// Generate target positions
vector<pll> targets;
for (ll x = 1; x <= N; x++) {
for (ll y = 1; y <= 2; y++) {
targets.push_back({x, y});
}
}
ll total_ops = 0;
set<ll> used_coins;
for (auto target : targets) {
ll min_dist = LLONG_MAX;
ll best_coin = -1;
for (ll i = 0; i < coins.size(); i++) {
if (used_coins.find(i) == used_coins.end()) {
ll dist = bfs(coins[i], target);
if (dist < min_dist) {
min_dist = dist;
best_coin = i;
}
}
}
total_ops += min_dist;
used_coins.insert(best_coin);
}
return total_ops;
}
};
int main() {
ios_base::sync_with_stdio(false);
cin.tie(NULL);
ll N;
cin >> N;
vector<pll> coins(2*N);
for (ll i = 0; i < 2*N; i++) {
cin >> coins[i].first >> coins[i].second;
}
Solution solution;
cout << solution.getMinimumOperations(N, coins) << "\n";
return 0;
}
