#include <iostream>
#include <vector>
#include <algorithm>
#include <map>

using namespace std;



int main() {
    map<int, std::pair<int, int>> volcanoes;
    vector<pair<int, std::pair<int, int>>> sorted;
    int samples, x, y;
    cin >> samples;

    while(samples--){
        cin >> x >> y;
        if (auto it = volcanoes.find(x) != volcanoes.end()){
            volcanoes.at(it).first = max(y, volcanoes.at(it).first);
            volcanoes.at(it).second = min(y, volcanoes.at(it).second);
        }else{
            volcanoes.insert({x, make_pair(y,y)});
        }
    }

    //first max
    int distance = 0, last_x = -1, pos_y = volcanoes.begin()->second.first;
    for (auto it:volcanoes) {
        distance += abs(it.second.first - it.second.second);
        if (last_x > 0) {
            distance += it.first - last_x;
            if (abs(pos_y - it.second.second) < abs(pos_y - it.second.first)){
                distance+=abs(pos_y - it.second.second);
                pos_y = it.second.first;
            } else {
                distance+=abs(pos_y - it.second.first);
                pos_y = it.second.second;
            }
        }
        last_x = it.first;
    }
    int result = distance;

    //first min
    distance = 0, last_x = -1, pos_y = volcanoes.begin()->second.second;
    for (auto it:volcanoes) {
        distance += abs(it.second.first - it.second.second);
        if (last_x > 0) {
            distance += it.first - last_x;
            if (abs(pos_y - it.second.second) < abs(pos_y - it.second.first)){
                distance+=abs(pos_y - it.second.second);
                pos_y = it.second.first;
            } else {
                distance+=abs(pos_y - it.second.first);
                pos_y = it.second.second;
            }
        }
        last_x = it.first;
    }
    result = min(result, distance);

    cout << result;

    return 0;
}