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<cstdio>
#include<algorithm>
#include<vector>
using namespace std;
int a[100100];
int check[100100];
int check1[100100];
vector<pair<int, int>> vt;
vector<pair<int, int>> vt1;
int main()
{
	int n;
	scanf("%d", &n);
	for (int i = 0; i < n; i++)
	{
		scanf("%d", &a[i]);
		if (i % 2)
			check[a[i]]++;
		else
			check1[a[i]]++;
	}
	for (int i = 0; i < 100100; i++)
	{
			vt.push_back({ check[i],i });
			vt1.push_back({ check1[i],i });
	}
	sort(vt.begin(), vt.end());
	sort(vt1.begin(), vt1.end());
	int t = vt.size();
	if (vt[t - 1].second == vt1[t - 1].second)
	{
		printf("%d", n - max(vt[t - 1].first + vt1[t - 2].first, vt[t - 2].first + vt1[t - 1].first));
	}
	else
		printf("%d", n - vt[t - 1].first - vt1[t - 1].first);
}