#include "bits/stdc++.h"
#define Rep(i,n) for(int i=0;i<(int)(n);i++)
#define For(i,n1,n2) for(int i=(int)(n1);i<(int)(n2);i++)
#define REP(i,n) for(ll i=0;i<(ll)(n);i++)
#define RREP(i,n) for(ll i=((ll)(n)-1);i>=0;i--)
#define FOR(i,n1,n2) for(ll i=(ll)(n1);i<(ll)(n2);i++)
#define RFOR(i,n1,n2) for(ll i=((ll)(n1)-1);i>=(ll)(n2);i--)
#define all(a)  (a).begin(),(a).end()
#define IOS std::cin.tie(0),std::ios::sync_with_stdio(false)

namespace idaten {

	using namespace std;
	using ll = int_fast64_t;
	using ull = uint_fast64_t;
	using P = std::pair<int64_t, int64_t>;
	template<typename T1, typename T2> inline bool chmin(T1& a, T2 b) { if (a > b) { a = b; return 1; }return 0; }
	template<typename T1, typename T2> inline bool chmax(T1& a, T2 b) { if (a < b) { a = b; return 1; }return 0; }
	template<class Type>struct is_vector : std::false_type {};
	template<class ValueType, class Alloc>struct is_vector<std::vector<ValueType, Alloc>> : std::true_type {};
	template <typename T> inline std::ostream& operator << (std::ostream& out, const std::vector<T>& v) {
		if (v.empty())return out;
		constexpr bool is_vector_v = is_vector<T>::value;
		if (is_vector_v)for (auto itr = v.begin(); itr != v.end();)out << (*itr), out << ((++itr != v.end()) ? "\n" : "");
		else for (auto itr = v.begin(); itr != v.end();)out << (*itr), out << ((++itr != v.end()) ? " " : "");
		return out;
	}
	inline void put() {}
	template<class T> inline void put(const T& first) { std::cout << first << "\n"; }
	template<class T, class... N> inline void put(const T& first, const N& ... rest) { std::cout << first << " "; put(rest...); }
	inline void putn() {}
	template<class T, class... N> inline void putn(const T& first, const N& ... rest) { std::cout << first << "\n"; putn(rest...); }

	template<typename T>
	struct edge {
		int to;
		T cost;
		edge(int t, T c) {
			to = t;
			cost = c;
		}
	};

	template<typename T>
	void dijkstra(int s, vector<vector<edge<T>>>& path, vector<T>& d) {
		using pi = pair<T, int>;
		priority_queue<pi, vector<pi>, greater<pi>> q;
		q.push(P(0, s));
		d[s] = 0;
		while (!q.empty()) {
			P p = q.top();
			q.pop();
			int v = p.second;
			if (d[v] < p.first)continue;
			REP(i, path[v].size()) {
				edge<T> e = path[v][i];
				if (d[e.to] > d[v] + e.cost) {
					d[e.to] = d[v] + e.cost;
					q.push(P(d[e.to], e.to));
				}
			}
		}
		return;
	}

	int proc(int l, int r, int& x) {
		if (l <= x && x <= r) {
			return 0;
		} else if(x < l) {
			int res = l - x;
			x = l;
			return res;
		} else {
			int res = x - r;
			x = r;
			return res;
		}
	}

	void solve() {
		IOS;
		int n;
		cin >> n;
		vector<int> l(n), r(n);
		REP(i, n) {
			cin >> l[i] >> r[i];
		}
		vector<int> used(n, 0);
		priority_queue<P> pl;
		priority_queue<P,vector<P>,greater<>> pr;
		REP(i, n) {
			pl.push(P(l[i], i));
			pr.push(P(r[i], i));
		}
		int now = 0;
		ll res = 0;
		ll tmp = 0;
		REP(i, n) {
			P t;
			if (i % 2 == 0) {
				while (used[pl.top().second]) {
					pl.pop();
				}
				t = pl.top();
				pl.pop();
			} else {
				while (used[pr.top().second]) {
					pr.pop();
				}
				t = pr.top();
				pr.pop();
			}
			used[t.second] = 1;
			int d = proc(l[t.second], r[t.second], now);
			tmp += d;
		}
		tmp += abs(now);
		chmax(res, tmp);
		now = 0;
		tmp = 0;
		fill(all(used), 0);
		while (!pr.empty()) {
			pr.pop();
		}
		while (!pl.empty()) {
			pl.pop();
		}
		REP(i, n) {
			pl.push(P(l[i], i));
			pr.push(P(r[i], i));
		}
		REP(i, n) {
			P t;
			if (i % 2 == 1) {
				while (used[pl.top().second]) {
					pl.pop();
				}
				t = pl.top();
				pl.pop();
			} else {
				while (used[pr.top().second]) {
					pr.pop();
				}
				t = pr.top();
				pr.pop();
			}
			used[t.second] = 1;
			int d = proc(l[t.second], r[t.second], now);
			tmp += d;
		}
		tmp += abs(now);
		chmax(res, tmp);
		put(res);
	}

} // namespace idaten

int main() {
	idaten::solve();
	return 0;
}

Measured memory_bytes: 4836