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: Wrong Answer)

use std::io::Read;

fn main() {
    let mut buf = String::new();
    std::io::stdin().read_to_string(&mut buf).unwrap();
    let mut iter = buf.split_whitespace();

    let n: usize = iter.next().unwrap().parse().unwrap();

    let mut a: Vec<u32> = Vec::with_capacity(n);
    let mut b: Vec<u32> = Vec::with_capacity(n);

    for _ in 0..n {
        a.push(iter.next().unwrap().parse().unwrap());
        b.push(iter.next().unwrap().parse().unwrap());
    }

    a.sort();
    b.sort();

    let ans: u32 = {
        if n % 2 == 1 {
            let left = a[n / 2];
            let right = b[n / 2];
            right - left + 1
        } else {
            let left = (a[n / 2 - 1] + a[n / 2]) as f32 / 2.0;
            let right = (b[n / 2 - 1] + b[n / 2]) as f32 / 2.0;
            ((right - left) * 2.0) as u32 + 1
        }
    };

    println!("{}", ans);
}