#include <vector>
#include <map>
#include <set>
#include <stack>
#include <queue>
#include <algorithm>
#include <numeric>
#include <sstream>
#include <iostream>
#include <iomanip>
#include <functional>
#define _USE_MATH_DEFINES
#include <cmath>
#include <climits>
#include <cstdlib>
#include <cstring>
#include <cfloat>
#include <cmath>
#include <ctime>
#include <cstdio>
#include <cassert>
using namespace std;

#define EPS 1e-12
#define ull unsigned long long
#define ll long long
#define VI vector<ll>
#define PII pair<ll, ll> 
#define VVI vector<vector<ll> >
#define REP(i,n) for(int i=0,_n=(n);(i)<(int)_n;++i)
#define RANGE(i,a,b) for(int i=(int)a,_b=(int)(b);(i)<_b;++i)
#define FOR(i,c) for(__typeof((c).begin())i=(c).begin();i!=(c).end();++i)
#define ALL(c) (c).begin(), (c).end()
#define ALLR(c) (c).rbegin(), (c).rend()
#define PB push_back
#define MP(a, b) make_pair(a, b)
#define POPCOUNT __builtin_popcount
#define POPCOUNTLL __builtin_popcountll
#define CLEAR(table, v) memset(table, v, sizeof(table));
#define PRINT1(table, D0) REP(d0, D0) cout<<table[d0]<<" "; cout<<"\n";
#define PRINT2(table, D0, D1) REP(d0, D0) { REP(d1, D1) cout<<table[d0][d1]<<" "; cout<<"\n"; }
#define PRINT3(table, D0, D1, D2) REP(d0, D0) { REP(d1, D1) { REP(d2, D2) cout<<table[d0][d1][d2]<<" "; cout<<"\n"; } cout<<"\n"; }
#define UNIFORM_DOUBLE(a, b) (((b-a)*(double)rand()/RAND_MAX)+a) // [a, b) 
#define UNIFORM_LL(a, b) (ll)UNIFORM_DOUBLE(a, b) // [a, b) 
#define IN(v, lo, hi) ((lo)<=(v) && (v)<(hi))
#define DD(v) cout<<#v<<": "<<v<<endl
template <typename T0, typename T1> std::ostream& operator<<(std::ostream& os, const map<T0, T1>& v) { for( typename map<T0, T1>::const_iterator p = v.begin(); p!=v.end(); p++ ){os << p->first << ": " << p->second << " ";} return os; }
template <typename T0, typename T1> std::ostream& operator<<(std::ostream& os, const pair<T0, T1>& v) { os << v.first << ": " << v.second << " "; return os; }
template <typename T> std::ostream& operator<<(std::ostream& os, const vector<T>& v) { for( int i = 0; i < (int)v.size(); i++ ) { os << v[i] << " "; } return os; }
template <typename T> std::ostream& operator<<(std::ostream& os, const vector<vector<T> >& v) { for( int i = 0; i < (int)v.size(); i++ ) { os << v[i] << endl; } return os; }
template <typename T> std::ostream& operator<<(std::ostream& os, const set<T>& v) { vector<T> tmp(v.begin(), v.end()); os << tmp; return os; }
template <typename T> std::ostream& operator<<(std::ostream& os, const deque<T>& v) { vector<T> tmp(v.begin(), v.end()); os << tmp; return os; }

#define MOD 1000000007LL
#define INF (1LL<<60)
#define FI first
#define SE second

int main() {
	cin.tie(0);
	ios::sync_with_stdio(false);
	ll N;
	ll l, r, i;
	while(cin>>N) {
		vector<pair<ll, pair<ll, ll>>> lri(N), rli(N);
		VI L(N), R(N);
		REP(i, N) {
			cin>>L[i]>>R[i];
			lri[i] = MP(L[i], MP(R[i], i));
			rli[i] = MP(R[i], MP(L[i], i));
		}
		sort(ALLR(lri));
		sort(ALL(rli));
		ll ans = 0;
		REP(loop, 2) {
			vector<bool> used(N);
			int lrii=0, rlii=0, uc=0;
			ll pos = 0;
			ll lans = 0;
			while(uc<N) {
				if(loop==0 || (loop==1 && uc>0)) {
					while(used[lri[lrii].SE.SE]) lrii++;
					uc++;
					l = lri[lrii].FI;
					r = lri[lrii].SE.FI;
					i = lri[lrii].SE.SE;
					used[i]=1;
//					DD(i);
					if(!(l<=pos&&pos<=r)) {
						if(pos<l) {
							lans += abs(pos-l);
							pos = l;
						} else {
							lans += abs(pos-r);
							pos = r;
						}
					}
					if(uc==N) break;
				}

				while(used[rli[rlii].SE.SE]) rlii++;
				uc++;
				r = rli[rlii].FI;
				l = rli[rlii].SE.FI;
				i = rli[rlii].SE.SE;
				used[i]=1;
//				DD(i);
				if(!(l<=pos&&pos<=r)) {
					if(pos<l) {
						lans += abs(pos-l);
						pos = l;
					} else {
						lans += abs(pos-r);
						pos = r;
					}
				}
			}
			lans += abs(pos);
				ans = max(ans, lans);
		}
		cout<<ans<<endl;
	}
	
	return 0;
}


Measured memory_bytes: 6528