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<bits/stdc++.h>

using namespace std;
using ll = long long;
using ld = long double;
#define rep(i,n) for(int i=0;i<(int)(n);i++)
#define reps(i,s,n) for(int i=(int)(s);i<(int)(n);i++)
const ll mod = ll(1e9) + 7;
const int INF = int(1e9);

int main() {
	cin.sync_with_stdio(false);
	int n;
	cin >> n;
	vector<int>v(n);
	rep(i, n)cin >> v[i];
	map<int, int>mp1, mp2;
	rep(i, n) {
		if (i % 2 == 0)mp1[v[i]]++;
		else mp2[v[i]]++;
	}
	vector<int>tmp1, tmp2;
	rep(i, n) {
		tmp1.push_back(v[i++]);
		tmp2.push_back(v[i]);
	}
	sort(tmp1.begin(), tmp1.end());
	sort(tmp2.begin(), tmp2.end());
	tmp1.erase(unique(tmp1.begin(), tmp1.end()), tmp1.end());
	tmp2.erase(unique(tmp2.begin(), tmp2.end()), tmp2.end());
	vector<pair<int, int>>p1, p2;
	rep(i, tmp1.size())p1.push_back({ mp1[tmp1[i]],tmp1[i] });
	rep(i, tmp2.size())p2.push_back({ mp2[tmp2[i]],tmp2[i] });
	sort(p1.begin(), p1.end());
	sort(p2.begin(), p2.end());
	if (p1[0].second == p2[0].second) {
		if (p1[0].first == p2[0].first) {
			cout << n - p1[0].first - max(p1[1].first, p2[1].first) << endl;
		}
		else if (p1[0].first < p2[0].first) {
			cout << n - p2[0].first - p1[1].first << endl;
		}
		else cout << n - p1[0].first - p2[1].first << endl;
	}
	else {
		cout << n - p1[0].first - p2[0].first << endl;
	}
	return 0;
}