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)

#include<stdio.h>
#include<stdlib.h>
#define TYPE int
int cmp_r(const void *a, const void *b) { return *(TYPE *)b - *(TYPE *)a; }
f[1000002];
int main() {
	int N, V, ans = 0;
	scanf("%d", &N);
	for (int i = 0; i < N; i++)
	{
		scanf("%d", &V);
		f[V - 1]++;
	}

	qsort(f, N, sizeof(int), cmp_r);
	if (f[1] == 0)
	{
		ans = f[0] / 2;
	}
	else if (f[2] == 0)
	{
		ans = abs(N / 2 - f[0]);
	}
	else
	{
		ans = abs(N / 2 - f[0]) + abs(N / 2 - f[1]);
	}
	printf("%d\n", ans);
	return 0;
}