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;
const int maxn=1e5+100;
int a[maxn],v1[maxn],v2[maxn];
int main()
{
    int n;scanf("%d",&n);
    for(int i=1;i<=n;i++)
    {
        int x;scanf("%d",&x);
        if(i%2) v1[x]++;
        else v2[x]++;
    }
    int ma1=0,id1,ma2=0,id2;
    int Ma1=0,Id1,Ma2=0,Id2;
    for(int i=1;i<maxn;i++)
    {
        if(v1[i]>ma1) ma2=ma1,id2=id1,ma1=v1[i],id1=i;
        else if(v1[i]>ma2) ma2=v1[i],id2=i;
        if(v2[i]>Ma1) Ma2=Ma1,Ma1=v2[i],Id2=Id1,Id1=i;
        else if(v2[i]>Ma2) Ma2=v2[i],Id2=i;
    }
    if(id1!=Id1) printf("%d\n",n-ma1-Ma1);
    else printf("%d\n",n-max(ma1+Ma2,ma2+Ma1));
    return 0;
}