#include <bits/stdc++.h>
#define gibon ios::sync_with_stdio(false); cin.tie(0);
#define fir first
#define sec second
#define pdd pair<double, double>
#define pii pair<int, int>
#define pll pair<ll, ll>
#define pmax pair<__int128, __int128>
#pragma GCC optimize("O3")
#pragma GCC optimize("Ofast")
#pragma GCC optimize("unroll-loops")
typedef long long ll;
using namespace std;
int dx[4]={0, 1, 0, -1}, dy[4]={1, 0, -1 , 0};
const int mxN=100020;
const int mxM=2500000;
const int mxK=105;
const int MOD=1000000007;
const ll INF=1000000000000000001;
int N;
int cntA[mxN][3], cntB[mxN][3];
ll ans;
int main()
{
gibon
cin >> N;
for(int i=0;i<2*N;i++)
{
int a, b;
cin >> a >> b;
if(a<1) ans+=1-a, a=1;
if(a>N) ans+=a-N, a=N;
if(b>2) ans+=b-2, b=2;
if(b<1) ans+=1-b, b=1;
cntA[a][b]++;
}
for(int i=1;i<=N;i++) for(int j=1;j<=2;j++) cntB[i][j]++;
for(int i=1;i<=N;i++)
{
for(int j=1;j<=2;j++)
{
int nval=min(cntA[i][j], cntB[i][j]);
cntA[i][j]-=nval; cntB[i][j]-=nval;
}
for(int j=1;j<=2;j++)
{
int nval=min(cntA[i][j], cntB[i][3-j]);
ans+=nval;
cntA[i][j]-=nval; cntB[i][3-j]-=nval;
}
for(int j=1;j<=2;j++) ans+=cntA[i][j]+cntB[i][j];
for(int j=1;j<=2;j++) cntA[i+1][j]+=cntA[i][j], cntB[i+1][j]+=cntB[i][j];
}
cout << ans;
}
