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 <cstdio>
#include <string>
#include <cmath>
#include <cctype>
#include <cstdlib>
#include <stack>
#include <queue>
#include <vector>
#include <algorithm>
#include <list>
#include<map>
#include<set>
using namespace std;

int main() {
    int n, k;
    cin >> n;
    vector<int> u, v;
    for (int i = 0; i < n;i++) {
        cin >> k;
        if (i % 2 == 0) u.push_back(k);
        else v.push_back(k);
    }
    sort(u.begin(), u.end());
    sort(v.begin(), v.end());
    int s1 = 1, s2 = 1, s3 = 1, s4 = 1, m1 = 0, m2 = 0, m3 = 0, m4 = 0, d1, d2;
    for (int i = 0; i < v.size() - 1;i++) {
        if (v[i] == v[i + 1]) s1++;
        else s1 = 1;
        if (m1 < s1) {
            m1 = s1;
            d1 = v[i];
        }
        if (u[i] == u[i + 1]) s2++;
        else s2 = 1;
        if (m2 < s2) {
            m2 = s2;
            d2 = u[i];
        }
    }
    for (int i = 0; i < v.size();i++) {
        if (v[i] == v[i + 1] && v[i] != d1) s3++;
        else s3 = 1;
        if (s3 > m3) m3 = s3;
        if (u[i] == u[i + 1] && u[i] != d2) s4++;
        else s4 = 1;
        if (s4 > m4) m4 = s4;
    }
    if (d1 == d2) cout << n - max(m1 + m4, m2 + m3) << endl;
    else cout << n - m1 - m2 << endl;
}