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: Wrong Answer)

#include<stdio.h>

int main()
{
    int n,a[100005],i,b=0;
    scanf("%d",&n);
    scanf("%d %d",&a[1],&a[2]);
    for(i=3;i<=n;i++)
    {
        scanf("%d",&a[i]);
    }
    for(i=3;i<=n;i=i+2)
    {
        if(a[1]==a[i])
           b=b*1;
        else 
        b=b+1;
    }
    for(i=4;i<=n;i=i+2)
    {
        if(a[2]==a[i])
        b=b*1;
        else
        b=b+1;
        
    }
    if(b==0 && a[1]!=a[2])
    printf("0\n");
    if(b==0 && a[1]== a[2])
    printf("%d\n",n/2);
    if(b!=0)
    printf("%d\n",b);
    
    return 0;
    
    
    
}