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

int main(){
  int n;
  cin >> n;
  vector<int> a(2*n);
  rep(i,2*n) cin >> a[i];
  auto b = a;
  reverse(b.begin(), b.end());
  ll res = 0;
  int i = 0, j = 0;
  while (n--) {
    int d1 = int(a[i] - '0') - int(a[i+1] - '0');
    int d2 = int(b[j] - '0') - int(b[j+1] - '0');
    if (d1 > d2) {
      res += d1;
      i += 2;
    } else {
      res += d2;
      j += 2;
    }
  }
  cout << res << endl;
  return 0;
}