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: Accepted)

fn main() {
    let mut buf: String = String::new();
    std::io::stdin().read_line(&mut buf).unwrap();
    let n: usize = buf.trim().parse::<usize>().unwrap();
    let mut v1: Vec<usize> = vec![0; 100001];
    let mut v2: Vec<usize> = vec![0; 100001];
    let mut buf: String = String::new();
    std::io::stdin().read_line(&mut buf).unwrap();
    let mut itr = buf.split_whitespace();
    while let Some(i) = itr.next() {
        v1[i.parse::<usize>().unwrap()] += 1;
        if let Some(i) = itr.next() {
            v2[i.parse::<usize>().unwrap()] += 1;
        }
    }
    let (mut m11,mut m12,mut m21,mut m22,mut m31,mut m32): (usize,usize,usize,usize,usize,usize) = (0,0,0,0,0,0);
    for x in 0..100001 {
        if v1[x] > m12 {
            if v1[x] > m11 {
                m12 = m11;
                m11 = v1[x];
                m31 = x;
            } else {
                m12 = v1[x];
            }
        }
        if v2[x] > m22 {
            if v2[x] > m21 {
                m22 = m21;
                m21 = v2[x];
                m32 = x;
            } else {
                m22 = v2[x];
            }
        }
    }
    println!("{}", if m31 != m32 {n-m11-m21} else {std::cmp::min(n-m11-m22,n-m12-m21)});
}