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 <algorithm>
#include <string>
#include <cmath>
#include <ctype.h>
#include <map>
#include <vector>
#include <stdlib.h>
#include <stdio.h>
#include <cctype>
#include <queue>
#include <set>
#include <list>
#define PI 3.141592653
#define rep(i,a,n) for(int i=a;i<(int)n;++i)
#define SZ(x) ((int)(x).size())	//size() unsigned -> int
#define DescSort(a) sort(a.begin(),a.end(),std::greater<int>())

using namespace std;
typedef long long ll;
const ll INF=1e9+7;

int main(void) {
	int n;
	vector<int> e(1e5 + 5, 0), o(1e5 + 5, 0);
	cin >> n;
	rep(i, 0, n) {
		int input;
		cin >> input;
		if (i % 2) {
			o[input]++;
		}
		else {
			e[input]++;
		}
	}
	int o_max_idx, e_max_idx;
	o_max_idx = distance(o.begin(), max_element(o.begin(), o.end()));
	e_max_idx = distance(e.begin(), max_element(e.begin(), e.end()));
	int ans = n - o[o_max_idx] - e[e_max_idx];
	if (o_max_idx == e_max_idx){
		int o_max_tmp = o[o_max_idx];
		int e_max_tmp = e[e_max_idx];
		o[o_max_idx] = 0;e[e_max_idx] = 0;
		int o_2_max_idx = distance(o.begin(), max_element(o.begin(), o.end()));
		int e_2_max_idx = distance(e.begin(), max_element(e.begin(), e.end()));
		ans = n - max(e[e_2_max_idx]+o_max_tmp, e_2_max_idx+o[o_max_tmp]);
	}
	cout << ans << endl;

	return 0;
}