#include <iostream>
#include <algorithm>
#define pii pair<int, int>
#define fst first
#define snd second
#define ll long long
using namespace std;
const ll INF = 1e18;
int N;
pii A[100001];
ll DP[2001][1001];
int main()
{
ios :: sync_with_stdio(0); cin.tie(0); cout.tie(0);
cin >> N;
for (int i = 0; i < 2 * N; i++) cin >> A[i].fst >> A[i].snd;
sort(A, A + 2 * N);
for (int i = 1; i <= N; i++) DP[0][i] = INF;
DP[0][0] = 0;
for (int i = 1; i <= 2 * N; i++)
{
for (int j = 0; j <= N; j++) DP[i][j] = INF;
for (int j = max(0, i - N); j <= i && j <= N; j++)
{
DP[i][j] = min(DP[i][j], DP[i - 1][j] + abs(A[i - 1].fst - i + j) + abs(A[i - 1].snd - 1));
if (j) DP[i][j] = min(DP[i][j], DP[i - 1][j - 1] + abs(A[i - 1].fst - j) + abs(A[i - 1].snd - 2));
}
}
cout << DP[2 * N][N] << "\n";
return 0;
}
