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<iostream>
#include<stdio.h>
#include<math.h>
#include<vector>
#include<algorithm>

using namespace std;

long long int a, b, c=0, d=0,e=0,f=0,g=0,h=0, n, i = 0, j = 0;
int p[100001], q[100001];
vector<int> vec1,vec2;
int main() {
	cin >> n;
	for (int k = 0; k < n; k++) {
		p[k+1] = 0;
	}
	for (int k = 0; k < n/2; k++) {
		cin >> a >> b;
		vec1.push_back(a);
		vec2.push_back(b);
	}
	sort(vec1.begin(), vec1.end());
	sort(vec2.begin(), vec2.end());
	a = 0;
	b = 0;
	for (int k = 0; k < n / 2; k++) {
		p[vec1[k]]++; q[vec2[k]]++;
		if (p[vec1[k]] > c) {
			if (vec1[k] != a) {
				e = a;
				g = c;
			}
			a = vec1[k];
			c = p[vec1[k]];
		}
		if (q[vec2[k]] > d) {
			if (vec2[k] != b) {
				f = b;
				h = d;
			}
			b = vec2[k];
			d = q[vec2[k]];
		}
	}
	if (a == b) {
		if (c + h >d + g) {
			b = f;
		}
		else {
			a = e;
		}
	}
	cout << n - (p[a] + q[b]) << '\n';
	return 0;

}