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: Accepted)

#include<stdio.h>
int MAX(int a,int b){return a<b?b:a;}
int main(){
  int n,i,a,m[2][2]={};
  int b[2][100010]={};
  int d[2][2]={};
  scanf("%d",&n);
  for(i=0;i<n;i++){
    scanf("%d",&a);
    b[i%2][a]++;
  }
  for(i=0;i<100005;i++){
    for(a=0;a<2;a++){
      if(m[1][a]<b[a][i]){
	d[1][a]=i;
	m[1][a]=b[a][i];
      }
      if(m[0][a]<b[a][i]){
	d[1][a]=d[0][a];
	m[1][a]=m[0][a];
	d[0][a]=i;
	m[0][a]=b[a][i];
      }
    }
  }
  //printf("%d %d %d %d\n",d[0][0],d[0][1],d[1][0],d[1][1]);
  if(d[0][0]==d[0][1])n-=MAX(m[0][0]+m[1][1],m[0][1]+m[1][0]);
  else n-=m[0][0]+m[0][1];
    //printf("%d %d\n",m[0],m[1]);
  printf("%d\n",n);
  return 0;
}