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;

#define rep(i,n) for(long long i=0; i<(long long)(n);i++)
#define rep2(i,s,n) for(long long i=(s); i<(long long)(n);i++)

#define mod 1e9+7;
#define inf 1e18+7;

typedef long long ll;


int main() {
    int n;cin>>n;
    vector<int>a(n),ecnt(101000),ocnt(101000);

    rep(i,n){
        cin>>a[i];
    }

    int emaxc=0,emaxn=0,esmaxc=0;
    int omaxc=0,omaxn=0,osmaxc=0;

    rep(i,n){
        if(i%2==0){
            ecnt[a[i]]++;
        }
        else {
            ocnt[a[i]]++;
        }
    }

    rep(i,101000){
        if(emaxc<ecnt[i]){
            emaxc=ecnt[i];
            emaxn=i;
        }
        else if (esmaxc<ecnt[i]&&ecnt[i]<emaxc) {
            esmaxc=ecnt[i];
        }
    }

    rep(i,101000){
        if(omaxc<ocnt[i]){
            omaxc=ocnt[i];
            omaxn=i;
        }
        else if (osmaxc<ocnt[i]&&ocnt[i]<omaxc) {
            osmaxc=ocnt[i];
        }
    }

    if(emaxn!=omaxn){
        cout<<n-emaxc-omaxc<<endl;
        return 0;
    }

    cout<<min(n-emaxc-osmaxc,n-esmaxc-omaxc)<<endl;

}