#include <bits/stdc++.h>
using namespace std;
#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define rep(i,n)   FOR(i,0,n)
#define pb emplace_back
typedef long long ll;
typedef pair<int,int> pint;

int L[100001],R[100001];
int main(){
    int n;
    cin>>n;
    int l,r;
    rep(i,n){
        cin>>l>>r;
        L[i]=l;
        R[i]=r;
    }
    sort(L,L+n,greater<int>());
    sort(R,R+n);
    ll mx=0;
    ll sum=0;
    rep(i,n){
        mx=max(mx,sum+max(L[i],-R[i]));
        sum+=L[i]-R[i];
        mx=max(mx,sum);
    }
    cout<<mx*2<<endl;
    return 0;
}
### Prompt

Please create a solution in Cpp to the following problem:

Takahashi and Aoki will play a game with a number line and some segments. Takahashi is standing on the number line and he is initially at coordinate 0. Aoki has N segments. The i-th segment is [L_i,R_i], that is, a segment consisting of points with coordinates between L_i and R_i (inclusive).

The game has N steps. The i-th step proceeds as follows:

* First, Aoki chooses a segment that is still not chosen yet from the N segments and tells it to Takahashi.
* Then, Takahashi walks along the number line to some point within the segment chosen by Aoki this time.



After N steps are performed, Takahashi will return to coordinate 0 and the game ends.

Let K be the total distance traveled by Takahashi throughout the game. Aoki will choose segments so that K will be as large as possible, and Takahashi walks along the line so that K will be as small as possible. What will be the value of K in the end?

Constraints

* 1 ≤ N ≤ 10^5
* -10^5 ≤ L_i < R_i ≤ 10^5
* L_i and R_i are integers.

Input

Input is given from Standard Input in the following format:


N
L_1 R_1
:
L_N R_N


Output

Print the total distance traveled by Takahashi throughout the game when Takahashi and Aoki acts as above. It is guaranteed that K is always an integer when L_i,R_i are integers.

Examples

Input

3
-5 1
3 7
-4 -2


Output

10


Input

3
1 2
3 4
5 6


Output

12


Input

5
-2 0
-2 0
7 8
9 10
-2 -1


Output

34

### Response

```cpp
#include <bits/stdc++.h>
using namespace std;
#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define rep(i,n)   FOR(i,0,n)
#define pb emplace_back
typedef long long ll;
typedef pair<int,int> pint;

int L[100001],R[100001];
int main(){
    int n;
    cin>>n;
    int l,r;
    rep(i,n){
        cin>>l>>r;
        L[i]=l;
        R[i]=r;
    }
    sort(L,L+n,greater<int>());
    sort(R,R+n);
    ll mx=0;
    ll sum=0;
    rep(i,n){
        mx=max(mx,sum+max(L[i],-R[i]));
        sum+=L[i]-R[i];
        mx=max(mx,sum);
    }
    cout<<mx*2<<endl;
    return 0;
}
```