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: Wrong Answer)


#include<bits/stdc++.h>
using namespace std;
const int maxn = 2e5 + 10;
struct Node {
    int val;
    int num;
} a[maxn], b[maxn];


bool cmp(Node a, Node b) {
    return a.num > b.num;
}

int main() {
    int n;
    cin >> n;
    int tmp;
    for(int i = 0; i < n; i ++) {
        scanf("%d", &tmp);
        if(i % 2 == 0) {
            a[tmp].num++;
            a[tmp].val = tmp;
        }
        else {
            b[tmp].num++;
            b[tmp].val = tmp;
        }
    }
    sort(a, a + maxn, cmp);
    sort(b, b + maxn, cmp);
    int ans = 0;
    if(a[0].val != b[0].val) 
        ans = n / 2 - a[0].num + n / 2 - b[0].num;
    else 
        ans = n - max(a[0].num + b[1].num, a[1].num + b[1].num);
    cout << ans <<endl;
}