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 Java8 (OpenJDK 1.8.0) (judge verdict: Accepted)

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

public class Main {

  public static void main(String[] args) {
    new Main().run();
  }

  public void run() {
    
    try(BufferedReader in = new BufferedReader(new InputStreamReader(System.in))) {

      int n = Integer.parseInt(in.readLine());
      String line = in.readLine();

      int[] seqA = new int[n/2];
      int[] seqB = new int[n/2];

      List<Integer> listA = new ArrayList<>();
      List<Integer> listB = new ArrayList<>();
      Map<Integer,Integer> mapA = new HashMap<>();
      Map<Integer,Integer> mapB = new HashMap<>();
      int offset=0,next=0;
      char regx = ' ';
      for(int i=0, j=0; i<n; i++, j= i >> 1) {
        if((next = line.indexOf(regx,offset)) == -1)
          next = line.length();
        Integer num = Integer.valueOf(line.substring(offset, next));
        offset = ++next;

        if((i & 1) == 0) {
          seqA[j] = num;
          if(mapA.containsKey(num)) {
            mapA.replace(num, mapA.get(num) + 1);
          } else {
            mapA.put(num, 1);
            listA.add(num);
          }
        }
        else {
          seqB[j] = num;
          if(mapB.containsKey(num)) {
            mapB.replace(num, mapB.get(num) + 1);
          } else {
            mapB.put(num, 1);
            listB.add(num);
          }
        }
      }

      int vma,vmb,xa,xb;
      vma = vmb = xa = xb =0;
      for (Integer var : listA) {
        int ma = mapA.get(var);
        if(vma < ma) {
          vma = ma;
          xa = var;
        }
      }
      for (Integer var : listB) {
        int mb = mapB.get(var);
        if(vmb < mb) {
          vmb = mb;
          xb = var;
        }
      }

      int cca,ccb;
      cca = ccb = 0;
      for (int i : seqA) {
        if(i != xa) cca++;
      }
      for (int i : seqB) {
        if(i != xb) ccb++;
      }

      int vma2,vmb2,xa2,xb2;
      vma2 = vmb2= xa2 = xb2 =0;
      int cca2,ccb2;
      cca2 = ccb2 = 0;
      int ans = 0;
      if(xa == xb) {
        for (Integer var : listA) {
          int ma = mapA.get(var);
          if(var != xa && vma2 < ma) {
            vma2 = ma;
            xa2 = var;
          }
        }
        for (Integer var : listB) {
          int mb = mapB.get(var);
          if(var != xb && vmb2 < mb) {
            vmb2 = mb;
            xb2 = var;
          }
        }
      
        for (int i : seqA) {
          if(i != xa2) cca2++;
        }
        for (int i : seqB) {
          if(i != xb2) ccb2++;
        }

        ans = cca2 > ccb2 ? cca + ccb2 : cca2 + ccb;
      }
      else {
        ans = cca + ccb;
      }

      System.out.println(ans);
    }
    catch(IOException e) {
      System.err.println(e);
    }
  }
}