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)

// Try AtCoder
// author: Leonardone @ NEETSDKASU

fn main() {
	let mut stdin = String::new();
    std::io::Read::read_to_string(
    	&mut std::io::stdin(),
        &mut stdin).unwrap();
	let mut stdin = stdin.split_whitespace();
    let mut get = || stdin.next().unwrap();
    macro_rules! get {
    	($t:ty) => (get().parse::<$t>().unwrap());
        () => (get!(i64));
    }
    
    let n = get!();
    let mut xs = vec![];
    let mut ys = vec![];
    for i in 0..n {
    	let x = get!();
    	if i % 2 == 0 {
        	xs.push(x);
        } else {
        	ys.push(x);
        }
    }
    xs.sort();
    ys.sort();
    use std::cmp::{max,min};
    let mut xe = -xs[0];
    let mut cc = 0;
    let mut xxx = vec![];
    for &x in xs.iter() {
    	if x == xe {
        	cc += 1;
        } else {
        	if xe > 0 {
            	xxx.push((-cc,xe));
            }
        	xe = x;
            cc = 1;
        }
    }
    xxx.push((-cc, xe));
    let mut ye = -ys[0];
    let mut yc = 0;
    let mut cc = 0;
    let mut yyy = vec![];
    for &y in ys.iter() {
    	if y == ye {
        	cc += 1;
        } else {
        	if ye > 0 {
            	yyy.push((-cc,ye));
            }
        	ye = y;
            cc = 1;
        }
    }
    yyy.push((-cc,ye));
    xxx.sort();
    yyy.sort();
    let len = (xxx.len(),yyy.len());
    let same = xxx[0].1 == yyy[0].1;
    let ans = match len {
    (1,1) if same => n/2,
    (1,1) => 0,
    (1,_) if same => n / 2 + yyy[1].0,
    (1,_) => n / 2 + yyy[0].0,
    (_,1) if same => n / 2 + xxx[1].0,
    (_,1) => n / 2 + xxx[0].0,
    _ if same => n + min(xxx[0].0+yyy[1].0, xxx[1].0+yyy[0].0),
    _ => n + xxx[0].0 + yyy[0].0,
    };
    println!("{}", ans);
}