#include<bits/stdc++.h>
using namespace std;
#define int long long 
int n;
struct node{
	int x,y,z;
}c[400400];
int id,ans;
int fa[200200];
int used[200200][2];
pair<int,int>a[200200],b[200200];
priority_queue<pair<int,int>,vector<pair<int,int> >,greater<pair<int,int> > >qa,qb;
bool cmp(node x,node y){
	return x.x>y.x;
}
int find(int x){
	if(fa[x]==x)return x;
	return fa[x]=find(fa[x]); 
}
void bing(int x,int y){
	x=find(x),y=find(y);
	fa[x]=y;
}
signed main(){
	cin>>n;
	for (int i=1,x,y;i<=n;i++)
	cin>>x>>y,c[++id]=(node){x,i,0},c[++id]=(node){y,i,1},
	qa.push({x,i}),qb.push({y,i}),fa[i]=fa[i+n]=i;
	sort(c+1,c+id+1,cmp);
	for (int i=1;i<=id;i++)
	if(used[c[i].y][c[i].z]==0){
		if(c[i].z==1){
			vector<pair<int,int> >t;
			while(qa.size()){
				pair<int,int>tmp=qa.top(); 
				if(used[tmp.second][0]==0){
					if(find(tmp.second)==find(c[i].y+n))t.push_back(tmp);
					else {
						used[tmp.second][0]=1;used[c[i].y][c[i].z]=1;
//						cout<<c[i].x<<" "<<tmp.first<<"****\n";
						ans+=abs(c[i].x-tmp.first);
						bing(tmp.second,c[i].y+n);qa.pop();
						break;
					}
				}
				qa.pop();
			}
			for (auto i:t)qa.push(i);
		}else{
			vector<pair<int,int> >t;
			while(qb.size()){
				pair<int,int>tmp=qb.top(); 
				if(used[tmp.second][1]==0){
					if(find(tmp.second+n)==find(c[i].y))t.push_back(tmp);
					else {
//						cout<<c[i].x<<" "<<tmp.first<<"\n";
						used[tmp.second][1]=1;used[c[i].y][c[i].z]=1;
						ans+=abs(c[i].x-tmp.first);
						bing(tmp.second+n,c[i].y);qb.pop();
						break;
					}
				}
				qb.pop();
			}
			for (auto i:t)qb.push(i);
		}
	}
	int xa=0,xb=0;
	for (int i=1;i<=id;i++){
		if(c[i].z==0&&used[c[i].y][0]==0)xa=c[i].x;
		if(c[i].z==1&&used[c[i].y][1]==0)xb=c[i].x;
	}
	
//	cout<<xa<<"*&&&&"<<xb<<"\n";
	ans+=abs(xa-xb);
	cout<<ans<<"\n";
}