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: Wrong Answer)

#![allow(unused_imports)]

use proconio::{input, fastout};
use proconio::marker::*;
use nalgebra::max;

fn main() {
    input! {
    n: usize,
    v: [usize; n]
    }
    let mut ec = vec![0; 100005];
    let mut oc = vec![0; 100005];
    for i in 0..n {
        if i % 2 == 0 {
            ec[v[i]] += 1;
        } else {
            oc[v[i]] += 1;
        }
    }
    let (mut em, mut om) = (0, 0);
    let (mut sem, mut som) = (0, 0);
    for i in 0..100005 {
        if ec[em] <= ec[i] {
            sem = em;
            em = i;
        }
        if oc[om] <= oc[i] {
            som = om;
            om = i;
        }
    }
    let ans = ec.iter().sum::<usize>() + oc.iter().sum::<usize>()
        - if em == om || em == som || om == sem {
        max(ec[em] + oc[som], ec[sem] + oc[om])
    } else {
        ec[em] + oc[om]
    };
    println!("{}", ans);
}