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 (GCC 5.4.1) (judge verdict: Runtime Error)

#include<stdio.h>
int main()
{
    int n;
    scanf("%d", &n);
    int i;
    int v[105];
    for (i = 0; i < n; i++)
        scanf("%d", &v[i]);
    int ans = n;
    int max;
    int g[105], k[105];
    for (i = 0; i < n; i++)
        if (i % 2 == 0)
            g[i / 2] = v[i];
        else
            k[i / 2] = v[i];
    int a;
    for (i = 0; i < n / 2 - 1; i++)
        if (g[i] > g[i + 1])
        {
            a = g[i];
            g[i] = g[i + 1];
            g[i + 1] = a;
            if (i > 0)
                i -= 2;
        }
    for (i = 0; i < n / 2 - 1; i++)
        if (k[i] > k[i + 1])
        {
            a = k[i];
            k[i] = k[i + 1];
            k[i + 1] = a;
            if (i > 0)
                i = 2;
        }
    max = 0;
    a = 1;
    g[n / 2] = k[n / 2] = -615;
    for (i = 1; i <= n / 2; i++)
    {
        if (g[i] == g[i - 1])
            a++;
        else
        {
            if (max < a)
                max = a;
            a = 1;
        }
    }
    ans -= max;
    max = 0;
    a = 1;
    for (i = 1; i <= n / 2; i++)
    {
        if (k[i] == k[i - 1])
            a++;
        else
        {
            if (max < a)
                max = a;
            a = 1;
        }
    }
    ans -= max;
    if (ans == 0 && v[0] == v[1])
        ans = n / 2;
    printf("%d\n", ans);
    return 0;
}