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;
    int v[110000];
    int count1[110000], count2[110000];
    int i,j;
    int value;
    int mode11=0, mode12=-1, mode21=0, mode22=-1;
    int modev11=0, modev12, modev21=0, modev22;

    for(i=0; i<110000; i++){
        count1[i] = 0;
        count2[i] = 0;
    }

    scanf("%d", &N);
    for(i=0; i<N; i++){
        scanf("%d", &v[i]);
    }
    modev12 = N/2;
    modev22 = N/2;

    for(i=0; i<N; i+=2){
        value = v[i];
        count1[value] += 1;
        if(modev11 < count1[value]){
            mode11 = value;
            modev11 = count1[value];
        }
    }
    for(i=0; i<N; i+=2){
        value = v[i];
        count2[value] += 1;
        if(modev12 < count2[value] && value!=mode11){
            mode12 = value;
            modev12 = count2[value];
        }
    }
    for(i=0; i<110000; i++){
        count1[i] = 0;
        count2[i] = 0;
    }
    for(i=1; i<N; i+=2){
        value = v[i];
        count1[value] += 1;
        if(modev21 < count1[value]){
            mode21 = value;
            modev21 = count1[value];
        }
    }
    for(i=1; i<N; i+=2){
        value = v[i];
        count2[value] += 1;
        if(modev22 < count2[value] && value!=mode11){
            mode22 = value;
            modev22 = count2[value];
        }
    }
    if(mode11 == mode21){
        if(modev12>modev22){
            printf("%d", N-modev12-modev21);
        }else{
            printf("%d", N-modev11-modev22);
        }
    }else{
        printf("%d", N-modev11-modev21);
    }

    return 0;
}