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 (1.42.0) (judge verdict: Accepted)

use proconio::input;

const MAX: usize = 100_001;

fn main() {
    input!(n: usize, v: [usize; n]);
    let mut a = vec![0; MAX];
    let mut b = vec![0; MAX];
    for i in 0..n {
        match i % 2 {
            0 => a[v[i]] += 1,
            1 => b[v[i]] += 1,
            _ => panic!(),
        }
    }
    let mut a: Vec<_> = a.iter().enumerate().map(|(i, &x)| (x, i)).collect();
    let mut b: Vec<_> = b.iter().enumerate().map(|(i, &x)| (x, i)).collect();
    a.sort_by_key(|&x| std::cmp::Reverse(x));
    b.sort_by_key(|&x| std::cmp::Reverse(x));
    println!(
        "{}",
        n - if a[0].1 != b[0].1 {
            a[0].0 + b[0].0
        } else {
            (a[0].0 + b[1].0).max(a[1].0 + b[0].0)
        }
    );
}