#include <bits/stdc++.h>
#pragma GCC optimize ("Ofast", "unroll-loops")
using namespace std;
#define ll long long
#define int ll
#define FOR(i,a,b) for (int i = (a); i<(b); i++)
#define REP(i,n) FOR(i,0,n)
#define REP1(i,n) FOR(i,1,n+1)
#define RREP(i,n) for (int i=(n)-1; i>=0; i--)
#define f first
#define s second
#define pb push_back
#define ALL(x) x.begin(),x.end()
#define SZ(x) (int)(x.size())
#define SQ(x) (x)*(x)
#define pii pair<int, int>
#define pdd pair<double ,double>
#define pcc pair<char, char>
#define endl '\n'
//#define TOAD
#ifdef TOAD
#define bug(x) cerr<<__LINE__<<": "<<#x<<" is "<<x<<endl
#define IOS()
#else
#define bug(...)
#define IOS() ios::sync_with_stdio(0), cin.tie(0), cout.tie(0)
#endif
const ll inf = 1ll<<60;
const int iinf=2147483647;
const ll mod = 1e9+7;
const ll maxn=1e5+5;
const double PI=acos(-1);
ll pw(ll x, ll p, ll m=mod){
ll ret=1;
while (p>0){
if (p&1){
ret*=x;
ret%=m;
}
x*=x;
x%=m;
p>>=1;
}
return ret;
}
ll inv(ll a, ll m=mod){
return pw(a,m-2);
}
//=======================================================================================
signed main (){
IOS();
int n; cin>>n;
vector<pii> vc(2*n);
vector<int> cnt1(n+1);
vector<int> cnt2(n+1);
int ans=0;
REP(i, 2*n){
cin>>vc[i].f>>vc[i].s;
pii g;
if (vc[i].s>=2){
ans+=vc[i].s-2;
g.s=2;
}
else {
ans+=1-vc[i].s;
g.s=1;
}
if (vc[i].f<=1){
ans+=1-vc[i].f;
g.f=1;
}
else if (vc[i].f>=n){
ans+=vc[i].f-n;
g.f=n;
}
else {
g.f=vc[i].f;
}
if (g.s==1){
cnt1[g.f]++;
}
else cnt2[g.f]++;
}
/*REP1(i, n){
cout<<cnt1[i]<<' ';
}
cout<<endl;
REP1(i, n){
cout<<cnt2[i]<<' ';
}
cout<<endl;
*/
int dx1=0, dx2=0;
REP1(i, n){
dx1+=cnt1[i]-1;
dx2+=cnt2[i]-1;
int k;
if (dx1>=0&&dx2<=0){
k=min(dx1, -dx2);
ans+=k;
dx1-=k;
dx2+=k;
}
else if (dx1<=0&&dx2>=0){
k=min(-dx1, dx2);
ans+=k;
dx1+=k;
dx2-=k;
}
ans+=abs(dx1);
ans+=abs(dx2);
}
cout<<ans<<endl;
}
