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 <bits/stdc++.h>

using namespace std;
typedef long long ll;

const int N = 1e5 + 5;

int arr[2][N];

int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(NULL), cout.tie(NULL);
    int n; cin >> n;
    for(int i=0; i<n; i++)
        cin >> arr[i & 1][(i >> 1)];

    int lastOdd = arr[1][0], currOdd = 1, bestOdd = 1, Odd = 0, lastBestOdd = 0;
    int lastEven = arr[0][0], currEven = 1, bestEven = 1, Even = 0, lastBestEven = 0;
    for(int i=1; i<n/2; i++)
    {
        if(arr[1][i] == lastOdd)
        {
            bestOdd = max(bestOdd, ++currOdd);
            if(bestOdd == currOdd)
                Odd = arr[1][i];
        }
        else
        {
            lastBestOdd = max(bestOdd, lastBestOdd);
            lastOdd = arr[1][i];
            currOdd = 1;
        }
        if(arr[0][i] == lastEven)
        {
            bestEven = max(bestEven, ++currEven);
            if(bestEven == currEven)
                Even = arr[0][i];
        }
        else
        {
            lastBestEven = max(bestEven, lastBestEven);
            lastEven = arr[0][i];
            currEven = 1;
        }
    }

    if(Odd == Even)
    {
        if(bestEven < bestOdd)
            bestEven = lastBestEven;
        else
            bestOdd = lastBestOdd;
    }

    int res = n - bestEven - bestOdd;
    cout << res << endl;
    return 0;
}