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 <iostream>
#include <string>
#include <vector>
#include <cassert>
#include <algorithm>
#include <functional>
#include <cmath>
#include <utility>
#include <numeric>
#include <map>
#include <iomanip>
using namespace std;

int main() {
	const int LARGE = 100010;
    int N; cin >> N;
	vector<int> v(N);
	for(int i = 0; i < N; i++) cin >> v[i];

	int ans = 0;

	vector<int> even(LARGE, 0);
	vector<int> odd(LARGE, 0);

	for(int i = 0; i < N; i++){
		if(i%2==0) even[v[i]]++;
		else odd[v[i]]++;
	}
	
	int even_max = 0, odd_max = 0, even_max2 = 0, odd_max2 = 0;
	for(int i = 0; i < LARGE; i++){
		if(even[even_max] < even[i]){
			even_max2 = even_max;
			even_max = i;
		}else if(even[even_max2] < even[i]){
			even_max2 = i;
		}
		if(odd[odd_max] < odd[i]){
			odd_max2 = odd_max;
			odd_max = i;
		}else if(odd[odd_max2] < odd[i]){
			odd_max2 = i;
		}
	}

	if(even_max == odd_max){
		cout << N - max(even[even_max] + odd[odd_max2], even[even_max2] + odd[odd_max]) << endl;
	}else{
		cout << N - even[even_max] - odd[odd_max] << endl;
	}
}