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>
#define NUM 100000
//疲れた


int main(){
	int n,i,ans;
	scanf("%d",&n);
	int c1[NUM],c2[NUM];
	int g = 1;	
	int gg = 0;
	int gn = 0;
	int ggn = 0;
	int k = 1;
	int kk = 0;
	int kn = 0;
	int kkn = 0;
	int deside,z;
	for(i = 0;i < NUM;i++){
		c1[i] = 0;
		c2[i] = 0;
		}
	for(i = 0;i < n;i++){
		deside = i % 2;
		scanf("%d",&z);
		if(deside == 0)
			c1[z]++;
		else
			c2[z]++;
		}
	for(i = 0;i < NUM;i++){
		if(c1[i] > g){
		gg = g;
		ggn = gn;
		g = c1[i];
		gn = i;
	}else if(c1[i] > gg){
		gg = c1[i];
		ggn = i;
	}
	if(c1[i] > k){
		kk = k;
		kkn = kn;
		k = c2[i];
		kn = i;
	}else if(c1[i] > kk){
		kk = c2[i];
		kkn = i;
	}
	}
	if(gn == kn){
		if(g + kk < gg + k){
			ans = n - gg - k;
	}else if(g == n / 2 && k == n / 2){
			ans = n / 2;
	}else{
			ans = n - g - kk;
	}
	}else{
			ans = n - g - k;
	}
	printf("%d",ans);
	return 0;
}