Problem:
Score : 500 points

Problem Statement

There are N integers X_1, X_2, \cdots, X_N, and we know that A_i \leq X_i \leq B_i.
Find the number of different values that the median of X_1, X_2, \cdots, X_N can take.

Notes

The median of X_1, X_2, \cdots, X_N is defined as follows. Let x_1, x_2, \cdots, x_N be the result of sorting X_1, X_2, \cdots, X_N in ascending order.

If N is odd, the median is x_{(N+1)/2};

if N is even, the median is (x_{N/2} + x_{N/2+1}) / 2.

Constraints

2 \leq N \leq 2 \times 10^5

1 \leq A_i \leq B_i \leq 10^9

All values in input are integers.

Input

Input is given from Standard Input in the following format:

N
A_1 B_1
A_2 B_2
:
A_N B_N

Output

Print the answer.

Sample Input 1

2
1 2
2 3

Sample Output 1

3

If X_1 = 1 and X_2 = 2, the median is \frac{3}{2};

if X_1 = 1 and X_2 = 3, the median is 2;

if X_1 = 2 and X_2 = 2, the median is 2;

if X_1 = 2 and X_2 = 3, the median is \frac{5}{2}.

Thus, the median can take three values: \frac{3}{2}, 2, and \frac{5}{2}.

Sample Input 2

3
100 100
10 10000
1 1000000000

Sample Output 2

9991

Solution in Rust (1.42.0) (judge verdict: Accepted)

#[allow(unused_imports)]
use itertools::Itertools;
#[allow(unused_imports)]
use num::*;
use proconio::input;
#[allow(unused_imports)]
use proconio::marker::*;
#[allow(unused_imports)]
use std::collections::*;

fn main() {
    input! {
        n: usize,
        abv: [(usize, usize); n]
    };
    if n % 2 == 0 {
        let mut v1 = abv.clone();
        v1.sort();
        let mut v2 = abv.clone();
        v2.sort_by_key(|x| x.1);
        let a = v2[n / 2 - 1].1 - v1[n / 2 - 1].0 + 1;
        let b = v2[n / 2].1 - v1[n / 2].0 + 1;
        let res = b + a - 1;
        println!("{}", res);
    } else {
        let mut v1 = abv.clone();
        v1.sort();
        let mut v2 = abv.clone();
        v2.sort_by_key(|x| x.1);
        let res = v2[n / 2].1 - v1[n / 2].0 + 1;
        println!("{}", res);
    }
    // let mut set = BTreeSet::new();
    // for a in 1..=2 {
    //     for b in 1..=2 {
    //         for c in 2..=5 {
    //             for d in 3..=4 {
    //                 let mut v = vec![a, b, c, d];
    //                 v.sort();
    //                 set.insert((v[1], v[2]));
    //             }
    //         }
    //     }
    // }
    // for (a, b) in set {
    //     println!("{}, {}", a, b);
    // }
}