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;
const int maxn = 1e5 + 28;
int a[maxn], cur1, cur2;
map <int, int> c, d, k;
int main(){
	int n, maxi1 = 0, maxi2 = 0, maxi = 0;
	cin >> n;
	for(int i = 0; i < n; i++){
		cin >> a[i];
		if(i % 2 == 0){
			c[a[i]] ++;
			if(c[a[i]] > maxi1){
				cur1 = a[i];
				maxi1 = c[a[i]];
			}
		}
		else{
			d[a[i]] ++;
			if(d[a[i]] > maxi2){
				cur2 = a[i];
				maxi2 = d[a[i]];
			}
		}
	}
	if(cur1 != cur2)
		return cout << (n / 2 - maxi1) + (n / 2 - maxi2), 0;
	else if(maxi1 > maxi2){
		for(int i = 1; i < n; i += 2)
			if(a[i] != cur1){
				k[a[i]] ++;
				maxi = max(k[a[i]], maxi);
			}
		cout << (n / 2 - maxi) + (n / 2 - maxi1); 
	}
	else{
		for(int i = 0; i < n; i += 2)
		if(a[i] != cur2){
			k[a[i]] ++;
			maxi = max(k[a[i]], maxi);
		}
		cout << (n / 2 - maxi) + (n / 2 - maxi2); 
	}
	
		
}