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 ll long long
#define ull unsigned long long
#define fi first
#define se second
using namespace std;
typedef pair<int,int> P;
const int M=1e5+10;
int n;
P m[2],s[2];
int a[2][M];
void fm(int x)
{
    //for(auto item: a[x])
    for(int i=0;i<M;i++)
    {
        P item=P(i,a[x][i]);
        if(item.se>m[x].se)
        {
            s[x]=m[x];
            m[x]=item;
        }
        else if(item.se>s[x].se)
            s[x]=item;
    }
}
int main()
{
    scanf("%d",&n);
    for(int i=0;i<n;i++)
    {
        int x;
        scanf("%d",&x);
        a[i&1][x]++;
    }
    fm(0),fm(1);
    if(m[0].fi==m[1].fi)
        printf("%d\n",n-max(m[0].se+s[1].se,m[1].se+s[0].se));
    else
        printf("%d\n",n-m[0].se-m[1].se);
    return 0;
}