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<cstdio>
#include<algorithm>
using namespace std;

#define MAXN 100000
int N;
int A[MAXN+5],cnt[2][MAXN+5];

int main(){
    scanf("%d",&N);
    for(int i=1;i<=N;i++)
        scanf("%d",A+i);
    for(int i=1;i<=N;i++)
        cnt[i%2][A[i]]++;
    int c1=0,c2=0;
    for(int i=1;i<=MAXN;i++){
        if(cnt[0][i]>cnt[0][c1])
            c1=i;
        if(cnt[1][i]>cnt[1][c2])
            c2=i;
    }
    if(c1!=c2)
        printf("%d",N-cnt[0][c1]-cnt[1][c2]);
    else{
        int tmp1=0,tmp2=0;
        for(int i=1;i<=MAXN;i++){
            if(i!=c1)
                tmp1=max(tmp1,cnt[0][i]);
            if(i!=c2)
                tmp2=max(tmp2,cnt[1][i]);
        }
        printf("%d",min(N-cnt[0][c1]-tmp2,N-cnt[1][c2]-tmp1));
    }
}