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>

int main()
{
    int n,i,j,ans,a,b,numa[100010]={0},numb[100010]={0};//バケット
	int maxa1=0,maxa2=0,maxb1=0,maxb2=0,maxnuma,maxnumb;
	scanf("%d",&n);
	for(i=0;i<(n/2);i++)
	{
		scanf("%d",&a);
		scanf("%d",&b);
		numa[a]++;
		numb[b]++;
	}
	for(j=1;j<=100000;j++)
	{
		if(maxa1<numa[j])
		{
			maxa1=numa[j];
			maxnuma=j;
		}
		else if(maxa2<numa[j])
		{
			maxa2=numa[j];
		}
	}
	
	for(j=1;j<=100000;j++)
	{
		if(maxb1<numb[j])
		{
			maxb1=numb[j];
			maxnumb=j;
		}
		else if(maxb2<numb[j])
		{
			maxb2=numb[j];
		}
	}
	
	if(maxnuma!=maxnumb)ans=(n-(maxa1+maxb1));
	else if((maxa1+maxb2)>(maxa2+maxb1))ans=(n-(maxa1+maxb2));
	else ans=(n-(maxa2+maxb1));
	
	printf("%d",ans);
}