#include "bits/stdc++.h"
using namespace std;
#define ar array
#define int long long
signed main(){
ios::sync_with_stdio(0); cin.tie(0);
int n; cin>>n; n <<= 1;
vector<ar<int, 2>> a(n);
for(int i=0;i<n;i++) cin>>a[i][0]>>a[i][1];
long long res = 0;
for(int i=0;i<n;i++){
if(a[i][1] > 2) res += (a[i][1] - 2), a[i][1] = 2;
if(a[i][1] < 1) res += (1 - a[i][1]), a[i][1] = 1;
}
vector<ar<int, 2>> b(n);
for(int i=0;i<n;i++){
b[i][0] = i / 2 + 1, b[i][1] = (i&1) + 1;
}
sort(a.begin(), a.end());
sort(b.begin(), b.end());
deque<int> tmp[2];
for(int i=0;i<n;i++){
if(a[i][1] == b[i][1]){
res += abs(a[i][0] - b[i][0]);
} else {
tmp[a[i][1] - 1].push_back(i);
}
}
while(!tmp[0].empty() && !tmp[1].empty()){
int i = tmp[0].front(), j = tmp[1].front();
if(a[i][0] > a[j][0]) swap(i, j);
if(a[j][0] <= b[i][0] || b[j][0] <= a[i][0]){
res += abs(a[i][0] - b[j][0]) + abs(a[j][0] - b[i][0]);
tmp[0].pop_front(), tmp[1].pop_front();
} else {
res += abs(a[i][0] - b[i][0]) + 1;
if(tmp[0].front() == i) tmp[0].pop_front();
else tmp[1].pop_front();
}
}
for(auto i : tmp[0]) res += abs(a[i][0] - b[i][0]) + 1;
for(auto i : tmp[1]) res += abs(a[i][0] - b[i][0]) + 1;
cout<<res<<"\n";
}
