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 big(a,b) ((a)<(b)?(a):(b))

int main(){
	int n,i,ashu[2][100001]={{0}},tmp,ans=0;
	scanf("%d",&n);
	for(i=0;i<n;i++){
		scanf("%d",&tmp);
		ashu[i%2][tmp]++;
	}
	int max[2][2]={{0,0},{0,0}};
	for(i=0;i<=100000;i++){
		if(ashu[0][max[0][0]]<ashu[0][i]){
			max[0][1]=max[0][0];
			max[0][0]=i;
		}else if(ashu[0][max[0][1]]<ashu[0][i]){
			max[0][1]=i;
		}
		if(ashu[1][max[1][0]]<ashu[1][i]){
			max[1][1]=max[1][0];
			max[1][0]=i;
		}else if(ashu[1][max[1][1]]<ashu[1][i]){
			max[1][1]=i;
		}
	}
	if(max[0][0]!=max[1][0])ans=n-ashu[0][max[0][0]]-ashu[1][max[1][0]];
	else {
		ans=big(n-ashu[0][max[0][0]]-ashu[1][max[1][1]],n-ashu[0][max[0][1]]-ashu[1][max[1][0]]);
	}
	printf("%d\n",ans);
	return 0;
}