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 C (GCC 5.4.1) (judge verdict: Wrong Answer)

int bw(const void *a, const void *b)
{
	return *(int*)b - *(int*)a;
}
#include<stdio.h>
#include<stdlib.h>
int main()
{
	int n, o[100010] = {}, e[100010] = {};
	int o1[100010] = {}, e1[100010] = {};
	int oo, ee;
	scanf("%d", &n);
	for (int i = 0; i < n; i+=2)
	{
		scanf("%d%d", &oo,&ee);
		o[oo]++; e[ee]++;
		o1[oo]++; e1[ee]++;
	}
	qsort(o1, 100010, sizeof(int), bw);
	qsort(e1, 100010, sizeof(int), bw);
	int maxe = 0, maxo = 0;
	oo = 0, ee = 0;
	for (int j = 0; j < 100010; j++)
	{
		if (e[j] == e1[0]) maxe = j;
		if (o[j] == o1[0]) maxo = j;
	}
	if (maxe != maxo)
	{
		printf("%d", n - e[maxe] - o[maxo]);
		return 0;
	}
	if (o1[1] < e1[1])
	{
		printf("%d", n - e1[0] - o1[1]);
		return 0;
	}
	else
	{
		printf("%d", n - e1[1] - o1[0]);
		return 0;
	}
	return 0;
}