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;
  int v[100000];
  int oddc[100000];
  int evenc[100000];
  
  scanf("%d",&n);
  
  int i;
  for(i=0;i<n;i++)
    scanf("%d",&v[i]);
  
  int max=0;
  for(i=0;i<n;i++)
    if(v[i]>max)
      max=v[i];
  
  for(i=0;2*i+1<n;i++)
    oddc[(v[2*i+1])]++;
  for(i=0;2*i<n;i++)
    evenc[(v[2*i])]++;
  
  int oddmaxindex=0,oddmax=0;
  int evenmaxindex=0,evenmax=0;
  
  for(i=0;i<max+1;i++){
    if(oddc[i]>oddmax){
      oddmaxindex=i;
      oddmax=oddc[i];
    }
  }
  for(i=0;i<max+1;i++){
    if(evenc[i]>evenmax){
      evenmaxindex=i;
      evenmax=evenc[i];
    }
  }
  if(evenmaxindex==oddmaxindex){
    int realom=oddmax;
    int realem=evenmax;
    evenc[evenmaxindex]=0;
    oddc[oddmaxindex]=0;
    oddmax=0;
    evenmax=0;
    for(i=0;i<max+1;i++){
      if(oddc[i]>oddmax){
        oddmaxindex=i;
        oddmax=oddc[i];
      }
    }
    for(i=0;i<max+1;i++){
      if(evenc[i]>evenmax){
        evenmaxindex=i;
        evenmax=evenc[i];
      }
    }
    if(oddmax>evenmax)
      evenmax=realem;
    else
      oddmax=realom;
  }

  printf("%d\n",n-evenmax-oddmax);
  return 0;
}