/*
                    !!!!!!                                                     
                    !!!!!!!!!!                                                 
                     !!!!!!!!!!!!!!!                                           
                       !!!!!!!!!!!!!!                                          
                     !!!!!!!!!!!!!!!                                           
                      !!!!!!!!!!!!                                             
                      !!!!!!!!!!!!                                             
                        !!!!!!!!!!!!                                           
                        !!!!!!!!                                               
                        !!!!!!!!!!                                             
                       !!!!!!!!!!!!!!                                          
                     !!!!!!!!!!!!!!!!                                          
                    !!!!!!!!!!!!!!!!                                  !!!!!    
                  !!!!!!!!!!!!!!!!!!!                               !!!!!!!!!! 
                 !!!!!!!!!!!!!!!!!!!!!!!                 !         !!!!!!!!!!  
            !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!              !!     !!!!!!!!!!!!    
           !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!        !!      !!!!!!!!       
            !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!      
             !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!!!!!!       
              !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!  !!!!!!!!!!!!       
       !!!!!! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!        !!!!!!        
      !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!      !!!!!         
          !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!        !!!          
        !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!        !          
          !!!!!! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!                       
           !!!!! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!                         
                  !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!                          
                 !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!                           
                  !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!                               
                  !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!                               
                  !!!!!!!!!!!!!!!!!!!!!!!!!!!!                                 
                  !!!!!!!!!!!!!!!!!!!!!!!!!!                                   
                  !!!!!!!!!!!!!!!!!!!!!!!!!                                    
                   !!!!!!!!!!!!!!!!!!!!!!!!                                    
                    !!!!!!!!!!!!!!!!!!!!                                       
                    !!!!!!!!!!!!!!!!!!!                                        
                     !!!!!!!!!!!!!!!!                                          
                      !!!!!!!!!!!!!!!!                                         
                      !!!!!!!!!!!!!!!                                          
                       !!!!!!!!!!!!!!                                          
                        !!!!!!!!!!!!                                           
                        !!!!!!!!!!!!                                           
                        !!!!!!!!!!!!                                           
                          !!!!!!!!                                             
                          !!!!!!                                               
                           !!!! 
*/                                               
#include <bits/stdc++.h>
#define MAXN 500005
#define mod 1000000007
using namespace std;
/*
 *  author  :  vivekcrux
 */
typedef long long ll; 
typedef pair<ll,ll> pll;

ll power(ll x,ll y,ll m=mod)
{
  ll ans = 1;
  while(y>0)
  {
    if(y&1)
    {
      ans = (ans*x)%m;
    }
    x = (x*x)%m;  
    y /= 2;
  }
  return ans%m;
}

ll modInverse(ll a, ll m=mod) 
{ 
    ll m0 = m; 
    ll y = 0, x = 1; 
  
    if (m == 1) 
      return 0; 
  
    while (a > 1) 
    { 
        // q is quotient 
        ll q = a / m; 
        ll t = m; 
  
        // m is remainder now, process same as 
        // Euclid's algo 
        m = a % m, a = t; 
        t = y; 
  
        // Update y and x 
        y = x - q * y; 
        x = t; 
    } 
  
    // Make x positive 
    if (x < 0) 
       x += m0; 
  
    return x; 
} 

ll eq(string a,string b)
{
    ll res = 0;
    for(ll i=0;i<a.length();i++)
    {
        if(a[i]!=b[i])
            res++;
    }
    return res;
}

int main()
{
  // freopen("input.txt","r",stdin);
  
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
    
  ll n,i,j,k;
  cin>>n;
  ll a[n+1],b[n+1];
  priority_queue<pll> th,ah;
  vector<bool> vis(n+1,false);
  for(i=1;i<=n;i++)
  {
      cin>>a[i]>>b[i];
      th.push({a[i]+b[i],i});
      ah.push({b[i]+a[i],i});
  }
  
  ll tp=0,ap=0;
  
  for(i=1;i<=n;i++)
  {
      if(i&1)
      {
          while(!th.empty() && vis[th.top().second])
            th.pop();

          if(b[th.top().second] < b[ah.top().second])
          {
            tp += a[ah.top().second];
            vis[ah.top().second] = true;
            ah.pop();
          }
          else
          {
            tp += a[th.top().second];
            vis[th.top().second] = true;
            th.pop();
          }
          // cout<<tp<<" ";
      }
      else
      {
          while(!ah.empty() && vis[ah.top().second])
            ah.pop();

          if(a[ah.top().second] < a[th.top().second])
          {
            ap += b[th.top().second];
            vis[th.top().second] = true;
            th.pop();
          }
          else
          {
            ap += b[ah.top().second];
            vis[ah.top().second] = true;
            ah.pop();
          }
          // cout<<ap<<" ";
      }
  }
  cout<<tp-ap;
  return 0;
}


Measured memory_bytes: 5220