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: Time Limit Exceeded)

#include <iostream>
#include <string>
using namespace std;

int unmuch(int i, int n, int* c){
    int temp = 0;
    int j;
    for (j=0; j<n/2; j++){
        if (c[j] != c[i]){
            temp++;
        }
    }
    return temp;
}

int much(int i, int* c){
    int temp = 0;
    int j;
    for (j=0; j<i; j++){
        if (c[j] == c[i]){
            return 1;
        }
    }
    return 0;
}

int main() {
    int n, i, j;
    cin >> n;

    int odd[n/2], even[n/2];
    
    // divide even and odd
    for (i=0; i<n; i++){
        if (i % 2 == 0)
            cin >> even[i/2];
        else 
            cin >> odd[i/2];
    }

    int ans = n, temp = 0;
    int even1st=1e5, even2nd=1e5, even1st_val, even2nd_val, temp_even;
    int odd1st=1e5, odd2nd=1e5, odd1st_val, odd2nd_val, temp_odd;
    int MAX = 10000;

    for (i=0; i<n/2; i++){

        temp_even = unmuch(i, n, even);
        // even array
        if (temp_even < even1st) {
            even2nd = even1st;
            even1st = temp_even;
            even2nd_val = even1st_val;
            even1st_val = even[i];
            }
        else if (temp < even2nd) {
            even2nd = temp_even;
            even2nd_val = even[i];
            }

        temp_odd = unmuch(i, n, odd);
        // odd array
        if (temp_odd < odd1st) {
            odd2nd = odd1st;
            odd1st = temp_odd;
            odd2nd_val = odd1st_val;
            odd1st_val = odd[i];
            }
        else if (temp_odd < odd2nd) {
            odd2nd = temp_odd;
            odd2nd_val = odd[i];
            }
        
    }

    
    if (even1st_val != odd1st_val) cout << even1st + odd1st << '\n';
    else if (even1st == 0 & odd1st == 0) cout << n / 2 << '\n';
    else cout << min(even1st + odd2nd, even2nd + odd1st) << '\n';
}