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 <cstdlib>
#include <cstdio>
#include <cmath>
#include <algorithm>
#include <map>
#include <stack>
#include <queue>
#include <set>
#include <cstring>

using namespace std;
// ascending order
#define vsort(v) sort(v.begin(), v.end())
// descending order
#define vsort_r(v) sort(v.begin(), v.end(), greater<ll>())
#define vunique(v) unique(v.begin(), v.end())
#define mp make_pair
#define ts(x) to_string(x)
#define rep(i, a, b) for(ll i = (ll)a; i < (ll)b; i++)
#define repm(i, a, b) for(ll i = (ll)a; i > (ll)b; i--)
#define bit(a) bitset<8>(a)
#define des_priority_queue priority_queue<ll, vector<ll>, greater<ll> >
#define all(v) (v).begin(), (v).end()
typedef long long ll;
typedef pair<ll, ll> P;
const ll INF = 1e18;

int main(){
	cin.tie(0);
	ios::sync_with_stdio(false);
	ll n;
	cin >> n;
	map<ll, ll> even;
	map<ll, ll> odd;
	vector<ll> tmp_v;
	rep(i, 0, n) {
		ll v;
		cin >> v;
		if(i % 2 == 0) even[v]++;
		else odd[v]++;
		tmp_v.push_back(v);
	}

	ll e1 = -1;
	ll e2 = -1;
	ll max_e1 = -1;
	ll max_e2 = -1;
	ll o1 = -1;
	ll o2 = -1;
	ll max_o1 = -1;
	ll max_o2 = -1;

	for(map<ll, ll>::iterator it = even.begin(); it != even.end(); it++) {
		if(max_e1 < it->second) {
			if(e2 != -1) {
				max_e2 = max_e1;
				e2 = e1;
			}
			e1 = it->first;
			max_e1 = it->second;
			continue;
		} 

		if(e2 != it->first and max_e2 < it->second) {
			e2 = it->first;
			max_e2 = it->second;
		}
	}

	for(map<ll, ll>::iterator it = odd.begin(); it != odd.end(); it++) {
		if(max_o1 < it->second) {
			if(o2 != -1) {
				max_o2 = max_o1;
				o2 = o1;
			}
			o1 = it->first;
			max_o1 = it->second;
			continue;
		} 

		if(o2 != it->first and max_o2 < it->second) {
			o2 = it->first;
			max_o2 = it->second;
		}
	}
	
	ll rsl1 = 0;
	ll rsl2 = 0;
	if(e1 != o1) {
		rep(i, 0, n) {
			if(i % 2 == 0) {
				if(e1 != tmp_v[i]) rsl1++;
			} else {
				if(o1 != tmp_v[i]) rsl1++;
			}
		}
		cout << rsl1 << endl;
	} else {
		rep(i, 0, n) {
			if(i % 2 == 0) {
				if(e1 != tmp_v[i]) rsl1++;
			} else {
				if(o2 != tmp_v[i]) rsl1++;
			}
		}
		rep(i, 0, n) {
			if(i % 2 == 0) {
				if(e2 != tmp_v[i]) rsl2++;
			} else {
				if(o1 != tmp_v[i]) rsl2++;
			}
		}
		ll rsl = min(rsl1, rsl2);
		cout << rsl << endl;
	}
}