Problem:
Score : 300 points

Problem Statement

A sequence a_1,a_2,... ,a_n is said to be /\/\/\/ when the following conditions are satisfied:

For each i = 1,2,..., n-2, a_i = a_{i+2}.

Exactly two different numbers appear in the sequence.

You are given a sequence v_1,v_2,...,v_n whose length is even.
We would like to make this sequence /\/\/\/ by replacing some of its elements.
Find the minimum number of elements that needs to be replaced.

Constraints

2 \leq n \leq 10^5

n is even.

1 \leq v_i \leq 10^5

v_i is an integer.

Input

Input is given from Standard Input in the following format:

n
v_1 v_2 ... v_n

Output

Print the minimum number of elements that needs to be replaced.

Sample Input 1

4
3 1 3 2

Sample Output 1

1

The sequence 3,1,3,2 is not /\/\/\/, but we can make it /\/\/\/ by replacing one of its elements: for example, replace the fourth element to make it 3,1,3,1.

Sample Input 2

6
105 119 105 119 105 119

Sample Output 2

0

The sequence 105,119,105,119,105,119 is /\/\/\/.

Sample Input 3

4
1 1 1 1

Sample Output 3

2

The elements of the sequence 1,1,1,1 are all the same, so it is not /\/\/\/.

Solution in Rust (1.15.1) (judge verdict: Wrong Answer)

use std::str::FromStr;

fn main () {
    let mut n = String::new();
    std::io::stdin().read_line(&mut n).unwrap();
    let n: usize = n.trim().parse().unwrap();

    let mut v = String::new();
    std::io::stdin().read_line(&mut v).unwrap();
    let mut v: Vec<isize> = v.trim().split_whitespace().flat_map(isize::from_str).collect();
    v.sort();

    let &v1 = v.iter().max().unwrap();
    let v2 = v.iter().rev().skip_while(|&&vi| vi == v1).next();
    println!("{}", if let Some(&v2) = v2 {
        v.iter().rev().skip_while(|&&vi| vi == v1 || vi == v2).count()
    } else {
        n / 2
    });
}