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++ (GCC 9.2.1) (judge verdict: Wrong Answer)

#include<bits/stdc++.h>
using namespace std;
#define IOS ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
#define int long long 
signed main() 
{
    IOS;    
    int n;
    cin>>n;
    map<int,int>mp1;
    map<int,int>mp2;
    for(int i=1;i<=n;i++){
    	int x;
    	cin>>x;
    	if(i%2){
    		mp1[x]++;
    	}
    	else mp2[x]++;
    }
    int ans=0;
    ans+=mp2.size()-1;
    ans+=mp1.size()-1;
    if(ans!=0)cout<<ans;
    else{
    	auto it=mp1.begin();
    	auto it2=mp2.begin();
    	if(it->first==it2->first)cout<<(n+1)/2;
    	else cout<<0;
    }
    
    return 0; 
}