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 int long long
const int MOD = 10007;

signed main(){
  int N; cin >> N;
  vector<int> a(N), num(100010), num1(100010);
  for(int i = 0; i < N; i++) {
  cin >> a[i];
  if(i % 2 == 0) num[a[i]]++;
  if(i % 2 == 1) num1[a[i]]++;
  }
  int p = max_element(num.begin(), num.end()) - num.begin();
  int q = max_element(num1.begin(), num1.end()) - num1.begin();
  int ans;
  if(p != q){
    ans = N - (num[p] + num1[q]);
  }
  if(p == q){
    sort(num.begin(), num.end()); reverse(num.begin(), num.end());
    sort(num1.begin(), num1.end()); reverse(num1.begin(), num1.end());
    ans = min(N - (num[0] + num1[1]), N - (num[1] + num1[0]));
  }
  cout << ans << endl;
}