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++ (Clang 10.0.0) (judge verdict: Accepted)

#include <cstdio>
#define maxn 100010
int cnt[2][maxn], M[2], Q[2], m[2], q[2];
int n;
int main() {
    scanf("%d", &n);
    for (int i = 1, x, p; i <= n; i++) {
        scanf("%d", &x); p = i % 2;
        cnt[p][x]++;
        if (M[p] < cnt[p][x]) M[p] = cnt[p][x], Q[p] = x;
    }
    if (Q[0] != Q[1]) {
        printf("%d\n", n - M[0] - M[1]);
        return 0;
    }
    for (int i = 1; i <= 100000; i++) {
        if (m[0] < cnt[0][i] && i != Q[0]) m[0] = cnt[0][i], q[0] = i;
        if (m[1] < cnt[1][i] && i != Q[1]) m[1] = cnt[1][i], q[1] = i;
    }
    if (M[0] - m[0] > M[1] - m[1]) printf("%d\n", n - M[0] - m[1]);
    else printf("%d\n", n - m[0] - M[1]);
    return 0;
}