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<iostream>
#include<string>
#include<vector>
#include<algorithm>
#include<map>
#include<set>
#include<cstdio>
#include<cmath>
#define repp(i,a,b) for(int i=(int)a;i<(int)b;++i)
#define repm(i,a,b) for(int i=(int)a;i>(int)b;--i)
using ll=long long;
static const ll mod = 1e9;
static const ll INF = 1LL << 50;
using namespace std;
#define odd 1
#define even 0

int main() {
	int n,count=1;
	cin >> n;
	int ans = n / 2;
	vector<int>v(n),vo,ve;
	vector<tuple<int, int,int>>vc;
	repp(i, 0, n)cin >> v[i];
	for (int i = 0; i < n - 1; i += 2)vo.push_back(v[i]);
	for (int i = 1; i < n; i += 2)ve.push_back(v[i]);
	sort(vo.begin(), vo.end()); sort(ve.begin(), ve.end());
	for (int i = 0; i < vo.size()-1; ++i) {
		if (vo[i] == vo[i + 1])++count;
		else {
			vc.push_back(make_tuple(count, vo[i],odd));
			count = 1;
		}
	}vc.push_back(make_tuple(count, vo[vo.size() - 1],odd));
		count = 1;
	for (int i = 0; i < ve.size() - 1; ++i) {
		if (ve[i] == ve[i + 1])++count;
		else {
			vc.push_back(make_tuple (count, ve[i],even));
			count = 1;
		}
	}vc.push_back(make_tuple (count, ve[ve.size() - 1],even));
	sort(vc.begin(), vc.end()); reverse(vc.begin(), vc.end());
	for (int i = 1;i<vc.size(); i++) {
		if (get<1>(vc[0]) != get<1>(vc[i])) {
			if (get<2>(vc[0]) != get<2>(vc[i])) {
				ans = n / 2 - get<0>(vc[0]) + n / 2 - get<0>(vc[i]);
				break;
			}
		}
	}
	cout << ans << endl; return 0;
}