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: Wrong Answer)

#include<utility>
#include<vector>
#include<algorithm>
#include<iostream>
using namespace std;

int n, a[2][100001], x;

int main(){
	int mini = 1001000,maxi = 0, poz = 0, poz_ = 0;
	cin >> n;
	for(int i = 1; i <= n; i++){
		cin >> x;
		a[i%2][x]++;
	}
	for(int i = 1; i <= n; i++){
		if(a[0][i] + a[1][i] < mini && a[0][i] + a[1][i]){
			mini = a[0][i] + a[1][i];
			poz_ = poz = i;
		}
	}
	for(int i = 0 ; i < 100001; i++){
		if(a[0][i] + a[1][i] > maxi){
			maxi = a[0][i] + a[1][i];
			poz_ = poz;
			poz = i;
		}
	}
	//cout << poz << " " << poz_ << "\n";
	if(poz == poz_)
		poz_ = 0;
	int x = a[0][poz], x1 = a[1][poz];
	int y = a[0][poz_], y1 = a[1][poz_];
	//cout << x  << " " << x1 << "\n" << y << " " << y1 << "\n";
	cout << min(n+n%2-x-y1, n+n%2-x1-y);	
}