#include<bits/stdc++.h>
#define ll long long
#define mk make_pair
#define fi first
#define se second
#define debug printf("ciallo\n");
const int N=2e5+10;
const int M=2e5+10;
const int MOD=1e9+7;
const int INF=0x3f3f3f3f;
using namespace std;
int n;
struct Node{
	int a,b,idx,lei;
}p[N];
bool cmp(Node q,Node w)
{
	if(q.lei!=w.lei) return q.lei>w.lei;
	else{
		if(q.lei>=0) return q.a<w.a;
		else return q.b>w.b;
	}
}
int main()
{
	freopen("service.in","r",stdin);
	freopen("service.out","w",stdout);
	
	cin>>n;
	for(int i=1;i<=n;i++){
		cin>>p[i].a;
		cin>>p[i].b;
		p[i].idx=i;
	}
	for(int i=1;i<=n;i++){
		if(p[i].a<p[i].b) p[i].lei=1;
		if(p[i].a==p[i].b) p[i].lei=0;
		if(p[i].a>p[i].b) p[i].lei=-1;
	}
	sort(p+1,p+n+1,cmp);
	int ta=0,tb=0;
	for(int i=1;i<=n;i++){
		ta+=p[i].a;
		tb=max(ta,tb)+p[i].b;
	}
	cout<<tb<<endl;
    return 0;
}