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;
int a[100001][2];
int main()
{
	int n, indeven, even = 0, alteven = 0, indodd, odd = 0, altodd = 0;
	scanf("%d", &n);
	for(int i = 0, j; i < n; ++i)
	{
		scanf("%d", &j);
		++a[j][i % 2];
	}
	for(int i = 1; i <= 100000; ++i)
	{
		if(even < a[i][0])
		{
			even = a[i][0];
			indeven = i;
		}
		else if(even == a[i][0] || alteven < a[i][0])
		{
			alteven = a[i][0];
		}
		if(odd < a[i][1])
		{
			odd = a[i][1];
			indodd = i;
		}
		else if(odd == a[i][1] || altodd < a[i][1])
		{
			alteven = a[i][1];
		}
	}
	if(indeven == indodd)
	{
		printf("%d\n", n - min(even + altodd, alteven + odd));
	}
	else
	{
		printf("%d\n", n - even - odd);
	}
}