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],x[100001],y[100001],n,p1,p2;
int main()
{
	memset(x,0,sizeof(x));
	memset(y,0,sizeof(y));
	
	scanf("%d",&n);
	for (int i=1;i<=n;i++)	
	{
		scanf("%d",&a[i]);
		if (i%2==1)
			x[a[i]]++;
		else
			y[a[i]]++;
	}
	int maxx=0,maxy=0;
	for (int i=1;i<=10000;i++)
	{
		if (x[i]>maxx) {maxx=x[i];p1=i;}
		
		if (y[i]>maxy) {maxy=y[i];p2=i;}
	}
	if (p1!=p2) 
	{
		cout<<n-maxx-maxy<<endl;
		
	}
	else
	{
		int maxxx=0,maxyy=0;
		for (int i=1;i<=10000;i++)
		{
			if (maxxx<x[i]&&i!=p1){maxxx=x[i];}
			if (maxyy<y[i]&&i!=p2){maxyy=y[i];}
		}
		if ((n-maxx-maxyy)<(n-maxy-maxxx))
			cout<<n-maxx-maxyy<<endl;
		else
			cout<<n-maxy-maxxx<<endl;			
	}
	
	return 0;
}