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;

#define MAX 100001

int main(){
	int n;	cin>>n;
	vector<int> even(MAX), odd(MAX);
	for(int i=0;i<MAX;i++) even[i]=odd[i]=0;
	
	int x;
	for(int i=1;i<=n;i++){
		cin>>x;
		if(i%2) odd[x]++;
		else even[x]++;
	}

	int e1=0, o1=0, e2=0, o2=0;

	int e1pos, o1pos;
	for(int i=0;i<MAX;i++){
		if(e1<even[i]){
			e1=even[i];
			e1pos=i;
		}

		if(o1<odd[i]){
			o1=odd[i];
			o1pos=i;
		}
	}

	for(int i=0;i<MAX;i++){
		if(e2<even[i]){
			if(i==e1pos) continue;
			e2=even[i];
		}

		if(o2<odd[i]){
			if(i==o1pos) continue;
			o2=odd[i];
		}
	}


	int ans;
	if(e1pos != o1pos){
		ans=(n/2 - e1) + (n/2 - o1);
	}else{
		int test1, test2;
		test1 = n-e1-o2;
		test2 = n-e2-o1;
		ans=min(test1, test2);
	}

	cout<<ans<<endl;

	return 0;
}