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;
#define inf 1000000007


int main() {
	ll n;
	cin>>n;
	ll a[100010],b[100010],x,y;
	for(int i=0;i<100010;i++){
		a[i]=b[i]=0;
	}
	while(cin>>x&&cin>>y){
		a[x]++;b[y]++;
	}
	ll a1,a2,a1n,a2n,b1,b2,b1n,b2n;
	a1=a2=b1=b2=0;
	for(int i=1;i<100010;i++){
		if(a1<=a[i]){
			a2=a1;a2n=a1n;
			a1=a[i];a1n=i;
		}
	}
	for(int i=1;i<100010;i++){
		if(b1<=b[i]){
			b2=b1;b2n=b1n;
			b1=b[i];b1n=i;
		}
	}
	cout << (a1n!=b1n? n-a1-b1: min(n-a1-b2,n-a2-b1));
	return 0;
}