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;
	scanf("%d",&n);
	int a[2][50000][2]={0},count[2]={0,0},j,i,tmp;
	for(i=0;i<n;i++){
		scanf("%d",&tmp);
		if(i%2==0){
			if(count[0]==0){
				a[0][count[0]][0]=tmp;
				a[0][count[0]][1]++;
				count[0]++;
			}
			else {
				for(j=0;j<count[0];j++){
					if(a[0][j][0]==tmp){
						a[0][j][1]++;
						break;
					}
				}
				if(j==count[0]){
					a[0][count[0]][0]=tmp;
					a[0][count[0]][1]++;
					count[0]++;
				}
			}
		}
		if(i%2==1){
			if(count[1]==0){
				a[1][count[1]][0]=tmp;
				a[1][count[1]][1]++;
				count[1]++;
			}
			else {
				for(j=0;j<count[1];j++){
					if(a[1][j][0]==tmp){
						a[1][j][1]++;
						break;
					}
				}
				if(j==count[1]){
					a[1][count[0]][0]=tmp;
					a[1][count[0]][1]++;
					count[1]++;
				}
			}
		}
	}
	int max[2]={0},mtmp[2]={0},yobi[2]={0,0},ytmp[2]={0};
	for(i=0;i<count[0];i++){
		if(max[0]<=a[0][i][1]){
			yobi[0]=max[0];
			ytmp[0]=mtmp[0];
			max[0]=a[0][i][1];
			mtmp[0]=a[0][i][0];
		}else if(yobi[0]<=a[0][i][1]){
			yobi[0]=a[0][i][1];
			ytmp[0]=a[0][i][0];
		}
	}
	for(i=0;i<count[1];i++){
		if(max[1]<=a[1][i][1]){
			yobi[1]=max[1];
			ytmp[1]=mtmp[1];
			max[1]=a[1][i][1];
			mtmp[1]=a[1][i][0];
		}else if(yobi[1]<=a[1][i][1]){
			yobi[1]=a[1][i][1];
			ytmp[1]=a[0][i][0];
		}
	}
	if(mtmp[0]!=mtmp[1]){
		printf("%d\n",n-max[0]-max[1]);
	}else{
		int ans=n-max[0]-yobi[1];
		if(n-max[1]-yobi[0]<ans)ans=n-max[1]-yobi[0];
		printf("%d\n",ans);
	}
	return 0;
}