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;

int a[100005],b[100005];

bool cmp(int a,int b)
{
    return a>b;
}

int main()
{
    int n;
    cin>>n;
    for(int i=0;i<n;i++)
    {
        int f;
        scanf("%d",&f);
        if(i&1) a[f]++;
        else b[f]++;
    }
    int mx=1;
    for(int i=1;i<=100000;i++) if(a[i]>a[mx]) mx=i;
    int mx1=1;
    for(int i=1;i<=100000;i++) if(b[i]>b[mx1]) mx1=i;
    sort(a,a+100001,cmp);
    sort(b,b+100001,cmp);
    if(mx!=mx1)
        printf("%d\n",n-a[0]-b[0]);
    else
        printf("%d\n",min(n-a[0]-b[1],n-a[1]-b[0]));
    return 0;
}