#include<bits/stdc++.h>
using namespace std;
const long long inf = (long long) 1e18 + 10;
const int inf1 = (int) 1e9 + 10;
#define int long long
#define dbl long double
#define endl '\n'
#define sc second
#define fr first
#define mp make_pair
#define pb push_back
#define all(x) x.begin(), x.end()
#define maxn 1010
int n, mark[maxn][maxn], dp[maxn][maxn];
vector<pair<int,int>> p;
int sol(int i, int j) {
if(mark[i][j]) return dp[i][j];
mark[i][j] = 1;
dp[i][j] = inf;
int id = i+j;
if(id == 2*n) {
return dp[i][j] = 0;
}
if(i != n) {
//pegar com id em cima
int val = abs(p[id].fr-i-1) + abs(p[id].sc-2);
dp[i][j] = min(sol(i+1,j)+val,dp[i][j]);
}
if(j != n) {
//pegar com id em cima
int val = abs(p[id].fr-j-1) + abs(p[id].sc-1);
dp[i][j] = min(sol(i,j+1)+val,dp[i][j]);
}
return dp[i][j];
}
void solve() {
cin >> n;
for(int i = 0; i < 2*n; i++) {
int x, y;
cin >> x >> y;
p.pb(mp(x,y));
}
sort(all(p));
cout << sol(0,0) << endl;
// for(int i = 0; i <= n; i++) {
// for(int j = 0; j <= n; j++) {
// cout << i << " " << j << " " << sol(i,j) << endl;
// }
// }
}
int32_t main() {
ios::sync_with_stdio(false); cin.tie(0);
// freopen("in.in", "r", stdin);
//freopen("out.out", "w", stdout);
int tt = 1;
// cin >> tt;
while(tt--) solve();
}
