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];
	multiset<int>st1, st2;
	rep(i, n) {
		if (i % 2 == 0)st1.insert(v[i]);
		else st2.insert(v[i]);
	}
	int cnt1 = 0, cnt2 = 0;
	int num1, num2;
	rep(i, n) {
		if (i % 2 == 0) {
			if (st1.count(v[i]) > cnt1) {
				cnt1 = st1.count(v[i]);
				num1 = v[i];
			}
		}
		else {
			if (st2.count(v[i]) > cnt2) {
				cnt2 = st2.count(v[i]);
				num2 = v[i];
			}
		}
	}
	if (num1 == num2) {
		cout << n - max(cnt1, cnt2) << endl;
	}
	else {
		cout << n - cnt1 - cnt2 << endl;
	}
	return 0;
}