#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const ll INF = 1e9;
const int MAX = 1000 + 10;
int N;
ll d0;
vector<vector<ll>> dp(MAX*2,vector<ll>(MAX*2,INF));
vector<pair<ll,ll>> p;
int main() {
cin >> N;
for (int i = 0; i < 2*N; i++) {
ll X,Y,x,y; cin >> X >> Y;
if (Y <= 1) y = 1;
else y = 2;
if (X <= 1) x = 1;
else if (1 < X && X < N) x = X;
else x = N;
p.push_back(make_pair(x,y));
d0 += abs(Y-y)+abs(X-x);
}
sort(p.begin(),p.end());
// for (auto t: p) {
// cout << t.first << " " << t.second << "\n";
// }
dp[0][0] = 0;
for (int i = 1; i <= 2*N; i++) {
ll x,y; tie(x,y) = p[i-1];
for (int a = 0; a <= i; a++) {
dp[i][a] = dp[i-1][a] + abs(x-(i-a)) + abs(y-2);
if (a > 0) dp[i][a] = min(dp[i][a],dp[i-1][a-1] + abs(x - a) + abs(y-1));
}
}
cout << d0 + *min_element(dp[2*N].begin(),dp[2*N].begin()+2*N) << "\n";
return 0;
}
