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 <vector>
#include <string>
#include <numeric>
#include <algorithm>
#include <cmath>
#include <functional>
#include <map>
#include <set>
#include <stack>
#include <deque>

#define INF 1000000000;
#define MOD 1000000007;
#define LIMIT 1000000000000000000;
typedef long long ll;
using namespace std;
typedef pair<int, int> P;

int main()
{
    int N; cin >> N;
    vector<int> A(N);
    map<int,int> dict; // elm, count
    for (int i = 0; i < N; i++) {
        int a; cin >> a;
        A[i] = a;
        dict[a]++;
    }
    if (dict.size() == 1) {
        cout << N / 2 << endl;
        exit(0);
    }

    vector<int> counts;
    for (auto p : dict) {
        counts.push_back(p.second);
        //cout << "first:" << p.first << " second:" << p.second << endl;
    }
    sort(counts.begin(), counts.end(), greater<int>());
    int cnt1 = counts[0];
    int cnt2 = counts[1];
    int ans = N - (cnt1 + cnt2);
    if (ans < 0) exit(1);
    cout << ans << endl;
}