#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using P = pair<int,int>;
#define rep(i,n) for(int i=0;i<n;i++)

const ll mod = ll(1e9) + 7;
const int INF = 1<<29;

int main(){
    int n;
    cin >> n;
    deque<ll> a;
    ll x;
    rep(i,2*n){
        cin >> x;
        a.push_back(x);
    }
    ll hom = 0l,tem = 0l;
    rep(i,n){
        if (a[0]-a[1]>a[a.size()-1]-a[a.size()-2]){
            hom += a[0];
            a.pop_front();
            tem += a[0];
            a.pop_front();
        } else {
            hom += a[a.size()-1];
            a.pop_back();
            tem += a[a.size()-1];
            a.pop_back();
        }
    }
    cout << hom - tem << endl;
    return 0;
}