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<algorithm>
using namespace std;

int most(int v[], int n, int m)
{
    int maxi = 0, ret = 0;
    for(int i = 1; i <= n; i++){
        if(maxi < v[i] && i != m){
            maxi = v[i];
            ret = i;
        }
    }
    return ret;
}

int main()
{
    int n, v0[100000] = {0}, v1[100000] = {0}, k, maxi[2] = {0};
    cin >> n;
    for(int i = 0; i < n / 2; i++){
        cin >> k;
        v0[k] += 1;
        maxi[0] = max(maxi[0], k);
        cin >> k;
        v1[k] += 1;
        maxi[1] = max(maxi[1], k);
    }
    int zero = most(v0, maxi[0], 0), one = most(v1, maxi[1], 0);
    cout << zero << ' ' << one << endl;
    if(zero != one){
        cout << n - v0[zero] - v1[one] << endl;
        return 0;
    }
    int zeroo = most(v0, n/2, zero), onee = most(v1, n/2, one);
    cout << n - (zeroo > onee ? v0[zeroo] + v1[one] : v0[zero] + v1[onee]) << endl;
    return 0;
}