#include<bits/stdc++.h>
#define int long long
using namespace std;
const int N=200100;
pair<int,int> a[N],b[N];
set<pair<int,int> >sa,sb;
int fa[N];
int find(int x){
	if(x==fa[x]) return x;
	return fa[x]=find(fa[x]);
}
void merge(int x,int y){
	x=find(x),y=find(y);
	if(x==y) return;
	fa[x]=y;
}
void solve(){
	int n;cin>>n;
	for(int i=1;i<=n;i++){
		fa[i]=i;
		int x;cin>>x;
		a[i]={x,i};
		cin>>x;
		b[i]={x,i};
	}
	int ans=0;
	for(int i=1;i<=n;i++) ans+=a[i].first-b[i].first;
	for(int i=1;i<=n;i++){
		sa.insert(a[i]);
		sb.insert(b[i]);
	}
	while(sa.size()&&sb.size()){
		auto p=sa.begin();
		auto [u1,v1]=*(p);
		auto q=--sb.end();
		auto [u2,v2]=*q;
		if(u1>=u2) break;
		if(find(v1)!=find(v2)){
			ans+=2*(u2-u1);
			merge(v1,v2);
			sa.erase(p);sb.erase(q);
		}
		else if(find(v1)==find(v2)&&sa.size()==1){
			ans+=2*(u2-u1);
			merge(v1,v2);
			sa.erase(p);sb.erase(q);
		}
		else{
			auto pp=p;
			pp++;
			auto qq=q;
			qq--;
			auto [u11,v11]=*pp;
			auto [u22,v22]=*qq;
				int x12=u22-u1,x21=u2-u11,x22=u22-u11;
				if(find(v11)==find(v22)) x22=-1e13;
				int minx=max(x12,x21);minx=max(minx,x22);
				if(minx<=0) break;
				if(x12==minx){
					ans+=x12*2;
					merge(v1,v22);
					sa.erase(p);sb.erase(qq);
				}
				else if(x21==minx){
					ans+=x21*2;
					merge(v11,v2);
					sa.erase(pp);sb.erase(q);
				}
				else{
					ans+=x22*2;
					merge(v11,v22);
					sa.erase(pp);sb.erase(qq);
				}
		}
	}
	cout<<ans<<"\n";
}

signed main(){
ios::sync_with_stdio(false);
cin.tie(0);cout.tie(0);
	solve();
}