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>

main() {
    int n;
    scanf("%d",&n);
    int cntEven[100001],cntOdd[100001];

    for (int i = 0; i < 100001; ++i) {
        cntEven[i]=0;
        cntOdd[i]=0;
    }

    int tmp;
    for (int i = 0; i < n; ++i) {
        scanf("%d",&tmp);
        if(i%2==0)cntEven[tmp]++;
        else cntOdd[tmp]++;
    }

    int odd[4]={0,0,0,0},even[4]={0,0,0,0};
    //[max1cnt,max1num,max2cnt,max2num;
    for (int i = 0; i < 100001; ++i) {
        if (even[0] < cntEven[i]) {
            even[2] = even[0];
            even[3] = even[1];
            even[0] = cntEven[i];
            even[1] = i;
        } else if (even[2] < cntEven[i]) {
            even[2] = cntEven[i];
            even[3] = i;
        }
        if (odd[0] < cntOdd[i]) {
            odd[2] = odd[0];
            odd[3] = odd[1];
            odd[0] = cntOdd[i];
            odd[1] = i;
        } else if (odd[2] < cntOdd[i]) {
            odd[2] = cntOdd[i];
            odd[3] = i;
        }
    }

    if(even[1]!=odd[1]){
        printf("%d",n-even[0]-odd[0]);
    } else{
        if(even[2]<odd[2]){
            printf("%d",n-even[2]-odd[0]);
        } else{
            printf("%d",n-even[0]-odd[2]);
        }
    }
}