#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define st first
#define nd second
int main()
{
int n;
cin>>n;
vector<pair<int,int>> h(n,{0,0});
vector<pair<int,int>> r(n+1,{1,1});
ll ans = 0;
for(int i =0 ;i<n*2;i++)
{
int x,y;
cin>>x>>y;
if(y >= 2)
{
ans += y-2;
y = 2;
}
if(y <= 1)
{
ans+= 1-y;
y = 1;
}
if(x > n)
{
ans+= x-n;
x = n;
}
if(x < 1)
{
ans+=1-x;
x = 1;
}
x--;
if(y == 1)
{
h[x].st++;
}
else
{
h[x].nd++;
}
}
//cout<<ans<<"\n";
for(int i = 0;i<n;i++)
{
//cout<<h[i].st<<" "<<h[i].nd<<" "<<r[i].st<<" "<<r[i].nd<<"\n";
if(r[i].st > h[i].st && r[i].nd > h[i].nd)
{
ans+= r[i].st - h[i].st + r[i].nd -h[i].nd;
r[i+1].st += r[i].st-h[i].st;
r[i+1].nd +=r[i].nd-h[i].nd;
}
else if(r[i].st <= h[i].st && r[i].nd <= h[i].nd)
{
ans+= h[i].st - r[i].st + h[i].nd -r[i].nd;
h[i+1].st += h[i].st-r[i].st;
h[i+1].nd +=h[i].nd-r[i].nd;
}
else if(r[i].st <= h[i].st && r[i].nd > h[i].nd)
{
int cu = h[i].st -r[i].st;
ans += cu;
if(r[i].nd-h[i].nd <= cu)
{
cu -= r[i].nd -h[i].nd;
h[i+1].st += cu;
}
else
{
int cu2 = r[i].nd - h[i].nd;
cu2 -= cu;
ans+=cu2;
r[i+1].nd += cu2;
}
}
else
{
int cu = h[i].nd -r[i].nd;
ans += cu;
if(r[i].st-h[i].st <= cu)
{
cu -= r[i].st-h[i].st;
h[i+1].nd += cu;
}
else
{
int cu2 = r[i].st - h[i].st;
cu2 -= cu;
ans+=cu2;
r[i+1].st += cu2;
}
}
}
cout<<ans;
}
