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 (1.6) (judge verdict: Wrong Answer)

package main

import (
	"bufio"
	"fmt"
	"os"
	"strconv"
)

var sc = bufio.NewScanner(os.Stdin)

func init() {
	sc.Split(bufio.ScanWords)
}

func nextInt() int {
	sc.Scan()
	i, e := strconv.ParseInt(sc.Text(), 10, 64)
	if e != nil {
		panic(e)
	}
	return int(i)
}

func nextLine() string {
	sc.Scan()
	return sc.Text()
}

func main() {
	n := nextInt()
	n1 := map[int]int{}
	n2 := map[int]int{}

	for i := 0; i < n; i++ {
		v := nextInt()
		if i%2 == 0 {
			n1[v]++
		} else {
			n2[v]++
		}
	}

	var n1max, _n1max, n2max, _n2max int
	for k, item := range n1 {
		if item > n1max {
			n1max = k
		} else {
			if item > _n1max {
				_n1max = k
			}
		}
	}

	for k, item := range n2 {
		if item > n2max {
			n2max = k
		} else {
			if item > _n2max {
				_n2max = k
			}
		}
	}

	// fmt.Printf("%#v %#v %#v %#v\n", n1max, _n1max, n2max, _n2max)

	var re1, re2 int
	if n1max != n2max {
		for k, item := range n1 {
			if k != n1max {
				re1 += item
			}
		}
		for k, item := range n2 {
			if k != n2max {
				re2 += item
			}
		}
		fmt.Println(re1 + re2)
	} else {
		var _re1, _re2 int
		for k, item := range n1 {
			if k != n1max {
				_re1 += item
			}
		}
		for k, item := range n2 {
			if k != _n2max {
				_re1 += item
			}
		}

		for k, item := range n1 {
			if k != _n1max {
				_re2 += item
			}
		}
		for k, item := range n2 {
			if k != n2max {
				_re2 += item
			}
		}

		if _re1 > _re2 {
			fmt.Printf("%#v\n", _re2)
		} else {
			fmt.Printf("%#v\n", _re1)
		}

	}
}