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,max=1,count,ans=0;
	scanf("%d",&n);
	int o[n/2+1],e[n/2+1];
	for(i=1;i<=n;i++){
		if(i%2==1) scanf("%d",&o[(i+1)/2]);
		else scanf("%d",&e[i/2]);
	}
	for(i=1;i<=n/2;i++){
	for(j=1;j<=n/2;j++){
		if(o[i]==e[j]){
			o[i]=-1,e[j]=-1;
		}
	}}
	for(i=1;i<=n/2;i++){
		count=0;
		for(j=1;j<=i;j++){
			if(o[i]==o[j]&&o[i]!=-1) count++;
		}
		if(max<count) max=count;
	}
	ans+=n/2-max;
	max=1;
	for(i=1;i<=n/2;i++){
		count=0;
		for(j=1;j<=i;j++){
			if(e[i]==e[j]&&e[i]!=-1) count++;
		}
		if(max<count) max=count;
	}
	ans+=n/2-max;
	printf("%d",ans);
}