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: Accepted)

#include<stdio.h>  
#include <bits/stdc++.h>
#include<stdlib.h>

using namespace std;

bool ok(int n) {
    stringstream ss;
    ss << n;
    string s;
    ss >> s;
    for(int i = 1; i < s.length(); i++) {
        if(s[i] != s[i - 1]) {
            return false;
        }
    }
    return true;
}

int main(){
    int n;
    cin >> n;
    int a[n];
    for(int i = 0; i < n; i++) {
        cin >> a[i];
    }
    int o, t, res = 0, om = 0, tm = 0, som = 0, tom = 0, so, st;
    map<int, int> data;
    for(int i = n; i >= 0; i -= 2) {
        data[a[i]]++;
        if(data[a[i]] > om) {
            so = o;
            som = om;
            o = a[i];
            om = data[a[i]];
        }
        else if(data[a[i]] > som) {
            so = a[i];
            som = data[a[i]];
        }
    }
    data.clear();
    for(int i = 1; i < n; i += 2) {
        data[a[i]]++;
        if(data[a[i]] > tm) {
            st = t;
            tom = tm;
            tm = data[a[i]];
            t = a[i];
        } 
        else if(data[a[i]] > tom) {
            st = a[i];
            tom = data[a[i]];
        }
    }
  //  cout << o << ' ' << so << endl << t << ' ' << st << endl;
    if(tm == om and tm == n / 2) {
        if(t == o) {
            cout << n / 2;
        }
        else cout << 0;
    }
    else {
       // cout << tm << ' ' << om << endl;
        
        if(o == t) {
            cout << min(n / 2 - om + n / 2 - tom, n / 2 - som + n / 2 - tm);
        }else   {
            tm = n / 2 - tm;
            // cout << tm << endl;
            om = n / 2 - om;
            cout << tm + om;
         }
        
    }
}