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;

typedef long long ll;

int main() {
	cin.tie(0);
    ios::sync_with_stdio(false);

    int N;
    cin >> N;

    vector<int> a(200000);
    vector<int> b(200000);

    int ac = 0, bc = 0;

    for(int i = 0; i < N; i++) {
        int v;
        cin >> v;
        if(i % 2) {
            b[v]++;
            bc++;
        } else {
            a[v]++; 
            ac++;
        }
    }

    int am = max_element(a.begin(), a.end()) - a.begin();
    int bm = max_element(b.begin(), b.end()) - b.begin();

    if(am == bm) {
        if(a[am] < b[bm]) {
            a[am] = 0;
            am = max_element(a.begin(), a.end()) - a.begin();
        } else {
            b[bm] = 0;
            bm = max_element(b.begin(), b.end()) - b.begin();
        }
    }

    cout << ac - a[am] + bc - b[bm] << endl;
}