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 Go (1.14.1) (judge verdict: Wrong Answer)

package main

import (
	"fmt"
)

func main() {
	var n int
	fmt.Scan(&n)
	vs := make([]int, n)
	for i := range vs {
		fmt.Scan(&vs[i])
	}

	even := map[int]int{}
	odd := map[int]int{}
	for i, v := range vs {
		if i%2 == 0 {
			even[v]++
		} else {
			odd[v]++
		}
	}

	ek1, ev1 := mapMax(even)
	ok1, ov1 := mapMax(odd)
	if ek1 != ok1 {
		fmt.Println(n - ev1 - ov1)
		return
	}

	if ev1 > ov1 {
		delete(odd, ok1)
		_, ov2 := mapMax(odd)
		fmt.Println(n - ev1 - ov2)
	} else {
		delete(even, ek1)
		_, ev2 := mapMax(even)
		fmt.Println(n - ov1 - ev2)
	}
}

func mapMax(m map[int]int) (mk int, mv int) {
	for k, v := range m {
		if v > mv {
			mv = v
			mk = k
		}
	}
	return
}