#include <bits/stdc++.h>
using namespace std;
#define rep(i,n) for(int (i)=0;(i)<(n);(i)++)
#define repp(i,m,n) for(int (i)=(m);(i)<(n);(i)++)
#define repm(i,n) for(int (i)=(n-1);(i)>=0;(i)--)
#define INF (1ll<<60)
#define all(x) (x).begin(),(x).end()
typedef long long lint;
const lint MOD =1000000007;
const lint MAX = 10000000;
using Graph =vector<vector<lint>>;
typedef pair<lint,lint> P;

 
lint fac[MAX], finv[MAX], inv[MAX];

void COMinit() // 二項係数を求める時は前処理としてCOMinit()をする
{
    fac[0] = fac[1] = 1;
    finv[0] = finv[1] = 1;
    inv[1] = 1;
    for (lint i = 2; i < MAX; i++)
    {
        fac[i] = fac[i - 1] * i % MOD;
        inv[i] = MOD - inv[MOD % i] * (MOD / i) % MOD;
        finv[i] = finv[i - 1] * inv[i] % MOD;
    }
}
 
// 二項係数計算
long long COM(lint n, lint k)
{
    if (n < k)
        return 0;
    if (n < 0 || k < 0)
        return 0;
    return fac[n] * (finv[k] * finv[n - k] % MOD) % MOD;
}

lint primary(lint num)
{
    if (num < 2) return 0;
    else if (num == 2) return 1;
    else if (num % 2 == 0) return 0; // 偶数はあらかじめ除く

    double sqrtNum = sqrt(num);
    for (int i = 3; i <= sqrtNum; i += 2)
    {
        if (num % i == 0)
        {
            // 素数ではない
            return 0;
        }
    }

    // 素数である
    return 1;
}
   long long modpow(long long a, long long n, long long mod) {
    long long res = 1;
    while (n > 0) {
        if (n & 1) res = res * a % mod;
        a = a * a % mod;
        n >>= 1;
    }
    return res;
}
    lint lcm(lint a,lint b){
        return a/__gcd(a,b)*b;
    }
  
  int main(){
   lint N;
   cin >>N;
   N*=2; 
   vector<lint> x(N);
   rep(i,N){
       lint a;
       cin>>a;
       x[i]=a;
   }
   lint a1=0,a2=0;
  while(!x.empty()){
        auto v=x.begin();
        lint g=*v;
        ++v;
        lint g1=*v;
        //cout<<g<<" "<<g1<<endl;
         v=x.end();
         --v;
         lint y=*v;
         --v;
         lint y1=*v;
       //   cout<<y<<" "<<y1<<endl;
         if(g-g1>=y-y1){
             a1+=g;
             a2+=g1;
             x.erase(x.begin());
             x.erase(x.begin());
         }else{
             a1+=y;
             a2+=y1;
             x.erase(x.end()-1);
            x.erase(x.end()-1);
         }
  }
  cout<<a1-a2<<endl;
   }