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)

// input macro
// ref: https://qiita.com/tanakh/items/0ba42c7ca36cd29d0ac8
macro_rules! input {
    (source = $s:expr, $($r:tt)*) => {
        let mut iter = $s.split_whitespace();
        input_inner!{iter, $($r)*}
    };
    ($($r:tt)*) => {
        let mut s = {
            use std::io::Read;
            let mut s = String::new();
            std::io::stdin().read_to_string(&mut s).unwrap();
            s
        };
        let mut iter = s.split_whitespace();
        input_inner!{iter, $($r)*}
    };
}

macro_rules! input_inner {
    ($iter:expr) => {};
    ($iter:expr, ) => {};

    ($iter:expr, $var:ident : $t:tt $($r:tt)*) => {
        let mut $var = read_value!($iter, $t);
        input_inner!{$iter $($r)*}
    };
}

macro_rules! read_value {
    ($iter:expr, ( $($t:tt),* )) => {
        ( $(read_value!($iter, $t)),* )
    };

    ($iter:expr, [ $t:tt ; $len:expr ]) => {
        (0..$len).map(|_| read_value!($iter, $t)).collect::<Vec<_>>()
    };

    ($iter:expr, chars) => {
        read_value!($iter, String).chars().collect::<Vec<char>>()
    };

    ($iter:expr, usize1) => {
        read_value!($iter, usize) - 1
    };

    ($iter:expr, $t:ty) => {
        $iter.next().unwrap().parse::<$t>().expect("Parse error")
    };
}


#[allow(unused_mut)]
fn main() {
    input!(
        n: usize,
        v: [usize; n],
    );

    let mx = 10_usize.pow(5) + 1;
    let mut odd: Vec<usize> = vec![0; mx];
    let mut even: Vec<usize> = vec![0; mx];

    for (i, &vi) in v.iter().enumerate() {
        if i%2 == 0 {
            odd[vi] += 1;
        }
        else {
            even[vi] += 1;
        }
    }

    let mut oddfirst = (0,0);
    let mut oddsecond = (0,0);
    for (oi, &oddi) in odd.iter().enumerate() {
        if oddi > oddfirst.1 {
            oddsecond = oddfirst.clone();
            oddfirst = (oi, oddi);
        }
        else if oddi > oddsecond.1 {
            oddsecond = (oi, oddi);
        }
    }

    let mut evenfirst = (0,0);
    let mut evensecond = (0,0);
    for (ei, &eveni) in even.iter().enumerate() {
        if eveni > evenfirst.1 {
            evensecond = evenfirst.clone();
            evenfirst = (ei, eveni);
        }
        else if eveni > evensecond.1 {
            evensecond = (ei, eveni);
        }
    }

    if oddfirst.0 == evenfirst.0 {
        if oddsecond.1 > evensecond.1 {
            println!("{}", n - evenfirst.1 - oddsecond.1);
        }
        else {
            println!("{}", n - oddfirst.1 - evensecond.1);
        }
    }
    else {
        println!("{}", n - oddfirst.1 - evenfirst.1);
    }


}