#include<bits/stdc++.h>
using namespace std;
#define int long long
priority_queue<pair<int,int>> q;
int shua[100005],shub[100005];
signed main(){
    freopen("nit.in","r",stdin);
    freopen("nit.out","w",stdout);
    int n;
    cin>>n;
    for(int i = 1;i<=n;i++){
        cin>>shua[i]>>shub[i];
        q.push({shua[i]-shub[i],i});
    }
    int a=0,b=0;
    for(int i = 1;i<=n;i++){
        int xu=q.top().second;
        q.pop();
        if(i==1){
            a+=shua[xu];
            b+=shub[xu];
            
        }
        else{
            if(i%2==1){
                a+=max(shua[xu],shub[xu]);
                b+=min(shua[xu],shub[xu]);
            }
            else{
                b+=max(shua[xu],shub[xu]);
                a+=min(shua[xu],shub[xu]);
                
            }
            
        }
        
        
        
    }
    cout<<a-b;
    return 0;
}