#include <bits/stdc++.h>
#define int long long 
using namespace std;
using Graph = vector<vector<int>>;

signed main(){
  int N;
  cin >> N;
  vector<int> A(2*N);
  for( int i = 0; i < 2*N; i++ ) cin >> A.at(i);
  
  int homu = 0;
  int tenn = 0;
  
  int r = 2*N-1;
  int l = 0;
  while( l < r ){
    int migi = A.at(r)-A.at(r-1);
    int hidari = A.at(l)-A.at(l+1);
    if( migi > hidari ){
      homu += A.at(r);
      tenn += A.at(r-1);
      r-= 2;
    }else{
      homu += A.at(l);
      tenn += A.at(l+1);
      l += 2;
    }
  }
  cout << homu-tenn << endl;
    
}