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,i,j,k,gu[100001],ki[100001],gun[100001],kin[100001],ng,nk;
    
   scanf("%d",&n);
   for (ng=nk=i=0;i<n;i++) {
     scanf("%d",&j);
     if (i%2==0) {
       for (k=0;k<ng;k++)
         if (gu[k]==j) break;
       if (k<ng) gun[k]++;
       else {
         gu[k]=j;gun[k]=1;
         ng++;
       }
     } else {
       for (k=0;k<nk;k++)
         if (ki[k]==j) break;
       if (k<nk) kin[k]++;
       else {
         ki[k]=j;kin[k]=1;
         nk++;
       }
     }
   }

   for (i=0;i<2;i++)
      for (j=i+1;j<ng;j++)
         if (gun[i]<gun[j]) {
            k=gun[i];gun[i]=gun[j];gun[i]=k;
            k=gu[i];gu[i]=gu[j];gu[i]=k;
         }

   for (i=0;i<2;i++)
      for (j=i+1;j<nk;j++)
         if (kin[i]<kin[j]) {
            k=kin[i];kin[i]=kin[j];kin[i]=k;
            k=ki[i];ki[i]=ki[j];ki[i]=k;
         }

   if (ki[0]!=gu[0]) printf("%d\n",n-kin[0]-gun[0]);
   else if (gun[0]+kin[1]>kin[0]+gun[1]) printf("%d\n",n-kin[1]-gun[0]);
   else printf("%d\n",n-kin[0]-gun[1]);
   return 0;
}