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>
#include<math.h>
#include<stdlib.h>

int compare_int(const int *a,const int *b){
    return *b- *a;
    }

int main(void){
    int n,a;
    scanf("%d",&n);
    int v[n];
    for(a = 0;a < n;a++){
    scanf("%d",&v[a]);
    }
    
    

    int v_o[n/2],v_e[n/2],j;

    for(j = 0;j < n/2;j++){
        v_e[j] = v[2*j];
        v_o[j] = v[2*j + 1];
    }
    
    qsort(v_o,n/2,sizeof(int),(int (*)(const void*,const void*))compare_int);
    qsort(v_e,n/2,sizeof(int),(int (*)(const void*,const void*))compare_int);
    
    int i,count_o = 1,count_e = 1;

    for(i = 0;i < n / 2;i++){
        if(v_o[i] == v_o[i + 1]){
            count_o++;
        }
    }

     for(i = 0;i < n / 2;i++){
        if(v_e[i] == v_e[i + 1]){
            count_e++;
        }
    }
    

    printf("%d",n - count_e - count_o);
    return 0;
}