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>

int a[100001],b[100001];
int ans;

int max(int x,int y){
	if(x>y)return x;
	return y;
}

int main(){
	int n;
	scanf("%d",&n);
	for(int i=0;i<n;i++){
		int v;
		scanf("%d",&v);
		if(i%2==0)a[v]++;
		else b[v]++;
	}
	
	int a1=0,a2=0,b1=0,b2=0;
	for(int i=1;i<=100000;i++){
		if(a[a1]<a[i]){
			a2=a1;
			a1=i;
		}
		else if(a[a2]<a[i])a2=i;
		if(b[b1]<b[i]){
			b2=b1;
			b1=i;
		}
		else if(b[b2]<b[i])b2=i;
	}
	if(a1==b1)ans=n-max(a[a1]+b[b2],a[a2]+b[b1]);
	else ans=n-(a[a1]+b[b1]);
	
	printf("%d\n",ans);
	return 0;
}