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: Runtime Error)

#include <stdio.h>

int main(){
  int n;
  scanf("%d\n",&n);
  //
  if(n==2){
    n = 0;
    printf("%d",n);
    return 0;
  }
  //
  int m = n/2;
  int a1[m];
  int a2[m];
  for(int i=0;i<m;i++){
    a1[i] = 0;
    a2[i] = 0;
  }
  int max1 = 1;
  int num1 = 0;
  int max2 = 1;
  int num2 = 0;
  int y,z;
  for(int i=0;i<n;i++){
    y = i%2;
    scanf("%d%*c", &z);
    if(y==0){
      a1[z] += 1;
    }else{
      a2[z] += 1;
    }
  }
  //
  for(int i=0;i<n;i++){
    if(a1[i] > max1){
      max1 = a1[i];
      num1 = i;
    }
    if(a2[i] > max2){
      max2 = a2[i];
      num2 = i;
    }
  }
  int answer = n - max1 - max2;
  if(answer==0 && num1 == num2){
    answer = n/2;
  }
  printf("%d",answer);
}