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: Accepted)

#include<stdio.h>
#include<stdlib.h>

int cmpnum(const void * n1, const void * n2)
{
	if (*(int *)n1 > *(int *)n2)
	{
		return -1;
	}
	else if (*(int *)n1 < *(int *)n2)
	{
		return 1;
	}
	else
	{
		return 0;
	}
}

int main(void)
{
	int i,n,o1,e1,ans=0;
	scanf("%d",&n);
	int o[100001]={0};
	int e[100001]={0};
	int b[100001]={0};
	for(i=0;i<n/2;i++){
		scanf("%d%d",&o1,&e1);
		b[o1]++;
		b[e1]++;
		o[o1]++;
		e[e1]++;
	}
	qsort(o, sizeof(o) / sizeof(o[0]), sizeof(int), cmpnum);
	qsort(e, sizeof(e) / sizeof(e[0]), sizeof(int), cmpnum);
	qsort(b, sizeof(b) / sizeof(b[0]), sizeof(int), cmpnum);
	
	if(b[0]==e[0]+o[0]){
		if(o[1]+e[0]>=e[1]+o[0])
			ans=n-(o[1]+e[0]);
		else
			ans=n-(o[0]+e[1]);
	}
	else
		ans=n-(o[0]+e[0]);
	printf("%d",ans);
	return 0;
}