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: Time Limit Exceeded)

#include <stdio.h>

int main(void) {
	int n,i,j;
	int cnt_a=100,cnt_b=100,tmp=0;
	scanf("%d",&n);
	int A[n];
	for(i=0;i<n;i++){
	scanf("%d",&A[i]);
	}
	for(i=0;i<n;i=i+2){
		tmp=0;
      if(A[i]!=A[i+2]){
		for(j=0;j<n;j=j+2){
			if(A[i]!=A[j]){
				tmp++;
			}
		}
      }
      if(i==0){
      	cnt_a=tmp;
      }else if(tmp<cnt_a&&tmp!=0){
			cnt_a=tmp;
		}
	}
	for(i=1;i<n;i=i+2){
		tmp=0;
      if(A[i]!=A[i+2]){
		for(j=1;j<n;j=j+2){
			if(A[i]!=A[j]){
				tmp++;
			}
		}
      }if(i==1){
      	cnt_b=tmp;
      }else if(tmp<cnt_b&&tmp!=0){
			cnt_b=tmp;
		}
	}
  
  if(cnt_b==cnt_a&&cnt_b==0){
    if(A[0]==A[1]){
      cnt_b=n/2;
    }
  }
	printf("%d",cnt_a+cnt_b);
	return 0;
}