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>
#define rep(i,l,r)for(int i=(l);i<(r);i++)
#define max(p,q)((p)>(q)?(p):(q))

int a[2][100010];
int main(){
	int n;
	scanf("%d",&n);
	for(int i=0;i<n;i++){
		int t;
		scanf("%d",&t);
		a[i%2][t]++;
	}
	int M[2][2]={},c[2][2];
	for(int i=1;i<=100000;i++){
		for(int j=0;j<2;j++){
			if(M[j][0]<=a[j][i]){
				M[j][1]=M[j][0];
				c[j][1]=c[j][0];
				M[j][0]=a[j][i];
				c[j][0]=i;
			}else if(M[j][1]<=a[j][i]){
				M[j][1]=a[j][i];
				c[j][1]=i;
			}
		}
	}
	int ans;
	if(c[0][0]==c[1][0])ans=M[0][0]+max(M[0][1],M[1][1]);
	else ans=M[0][0]+M[1][0];
	printf("%d",n-ans);
}