#include <iostream>
#include <vector>
#include <algorithm>
#include <cmath>
#include <queue>
#include <string>
#include <map>
#include <set>
#include <tuple>
#include <deque>
#include <numeric>
#include <bitset>
#include <iomanip>
#include <cassert>
#include <chrono>
#include <random>
#include <limits>
#include <iterator>
#include <functional>
#include <sstream>
using namespace std;

typedef long long ll;
typedef pair<int, int> P;
typedef pair<int, double> Pid;
typedef pair<double, int> Pdi;
typedef pair<ll, int> Pl;
typedef pair<int, pair<int, int>> PP;
const double PI = 3.1415926535897932;   // acos(-1)
const double EPS = 1e-15;
const int INF = 1001001001;
const int mod = 1e+9 + 7;

#define chmax(x, y) x = max(x, y)
#define chmin(x, y) x = min(x, y)
#define chadd(x, y) x = (x + y) % mod

int main(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    int n;
    cin >> n;
    int sz = n * 2;
    vector<ll> a(sz);
    for(int i = 0; i < sz; ++i)    cin >> a[i];
    
    int left = 0, right = sz - 1;
    ll res = 0;
    int remain = sz;
    while(remain > 2){
        ll foo = a[left] - a[left + 1];
        ll bar = a[right] - a[right - 1];
        if(foo >= bar){
            res += foo;
            left = left + 2;
        }
        else{
            res += bar;
            right = right - 2;
        }
        remain -= 2;
    }
    if(remain % 2 == 0){
        ll foo = a[left] - a[right];
        ll bar = a[right] - a[left];
        res += max(foo, bar);
    }
    else{
        res += a[left];
    }
    cout << res << endl;
}