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)

using namespace std;
#include <iostream>
#include <algorithm>
#include <vector>
#include <map>
#define N_MAX (100000)

int main(){

    int n;
    int v[N_MAX];
    
    cin >> n;
    for(int i=0;i<n;i++){
        cin >> v[i];              
    }

    map<int, int> mp1, mp2;
    for(int i = 0; i < n; i += 2) mp1[v[i]]++;
    for(int i = 1; i < n; i += 2) mp2[v[i]]++;
    
    int mp1_1st_v = 0;
    int mp1_1st_c = 0;
    int mp1_2nd_v = 0;
    int mp1_2nd_c = 0;

    for(auto it : mp1){
        if(it.first > mp1_1st_v){
            mp1_1st_v = it.first;
            mp1_1st_c = it.second;
        }
    }

    mp1.erase(mp1_1st_v);

    for(auto it : mp1){
        if(it.first > mp1_1st_v){
            mp1_2nd_v = it.first;
            mp1_2nd_c = it.second;
        }
    }

    int mp2_1st_v = 0;
    int mp2_1st_c = 0;
    int mp2_2nd_v = 0;
    int mp2_2nd_c = 0;

    for(auto it : mp1){
        if(it.first > mp2_1st_v){
            mp2_1st_v = it.first;
            mp2_1st_c = it.second;
        }
    }

    mp2.erase(mp2_1st_v);

    for(auto it : mp1){
        if(it.first > mp2_1st_v){
            mp2_2nd_v = it.first;
            mp2_2nd_c = it.second;
        }
    }

    int ans;

    if(mp1_1st_v == mp2_2nd_v){
        ans = min(n-(mp1_1st_c+mp2_2nd_c),n-(mp1_2nd_c+mp2_1st_c));
    }else{
        ans = n-(mp1_1st_c+mp2_1st_c);
    }

    cout << ans << endl;

    return 0;
}