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 <bits/stdc++.h>

using namespace std;

int n,v[110000],memo[2][110000],hoge[2][2],huga[2][2],x,z,maxx;

int main() {
    cin >> n;
    for (x=0 ; x<n ; x++) {
        cin >> v[x];
        memo[ x%2 ][ v[x] ]++;
        if (maxx < v[x]) maxx = v[x];
    }

    for (z = 0 ; z < 2 ; z++) {
        for (x = 0; x <= maxx; x++) {
            if (hoge[z][0] < memo[z][x]) {
                hoge[z][1] = hoge[z][0];
                hoge[z][0] = memo[z][x];
                huga[z][1] = huga[1][0];
                huga[z][0] = x;
            }
            else if(hoge[z][1] < memo[z][x]){
                hoge[z][1] = memo[z][x];
                huga[z][1] = x;
            }
        }
    }

    if(huga[0][0] != huga[1][0]) cout << n-hoge[0][0]-hoge[1][0] << "\n";
    else
        if(hoge[0][0]+hoge[1][1] > hoge[0][1]+hoge[1][0]) cout << n-hoge[0][0]-hoge[1][1] << "\n";
        else cout << n-hoge[0][1]-hoge[1][0] << "\n";
}