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++14 (GCC 5.4.1) (judge verdict: Accepted)

#include <bits/stdc++.h>
using namespace std;
int c_a[100005],c_b[100005];
int main(){
    int n;
    cin >> n;
    int a[n/2],b[n/2];
    for(int i=0;i<n;i++){
        if(i%2==0){
            cin >> a[i/2];
            c_a[a[i/2]]++;
        }
        else{
            cin >> b[(i-1)/2];
            c_b[b[(i-1)/2]]++;
        }
    }
    int max_a=0;
    int sec_a=0;
    int max_b=0;
    int sec_b=0;
    for(int i=0;i<n/2;i++){
        if(c_a[max_a]<=c_a[a[i]] && max_a!=a[i]){
            sec_a=max_a;
            max_a=a[i];
        }
        else if(c_a[sec_a]<=c_a[a[i]] && sec_a!=a[i] && max_a!=a[i]){
            sec_a=a[i];
        }
        if(c_b[max_b]<=c_b[b[i]] && max_b!=b[i]){
            sec_b=max_b;
            max_b=b[i];
        }
        else if(c_b[sec_b]<=c_b[b[i]] && sec_b!=b[i] && max_b!=b[i]){
            sec_b=b[i];
        }      
    }
    if(max_a!=max_b)cout << n-c_a[max_a]-c_b[max_b] << endl;
    else if(c_a[sec_a]>c_b[sec_b])cout << n-c_a[sec_a]-c_b[max_b] << endl;
    else cout << n-c_a[max_a]-c_b[sec_b] << endl;
}