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>
#define rep(i,n) for (int i = 0; i < (n); i++)
using namespace std;
using ll = long long;
using P = pair<int,int>;
const int MOD=1000000007;
 
int main() {
  int n;
  cin >> n;
  map<int,int> a, b;
  rep(i,n/2) {
    int x, y;
    cin >> x >> y;
    a[x]++; b[y]++;
  }
  int maxa=0, maxb=0;
  int maxa2=0, maxb2=0;
  int A, B;
  for(auto p: a) {
    if(maxa<p.second) {
      maxa=p.second;
      A=p.first;
    }
  }
  for(auto p: a) {
    if(p.first==A) continue;
    maxa2=max(maxa2,p.second);
  }
  for(auto p: b) {
    if(maxb<p.second) {
      maxb=p.second;
      B=p.first;
    }
  }
  for(auto p: b) {
    if(p.first==B) continue;
    maxb2=max(maxb2,p.second);
  }
 
  int ans=n-maxa-maxb;
  if(A==B) ans=min(n-maxa-maxb2,n-maxa2-maxb);
  cout << ans << endl;
}