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: Accepted)

#include <stdio.h>
#include <stdlib.h>

int main(void){
	int n, *v, v1[100001], v2[100001], max1, max2, max3, max4, i1, i2, count1=1, count2=1;
	scanf("%d", &n);
	v = (int *)malloc(sizeof(int)*n);
	for (int i = 0; i < n; ++i){
		scanf("%d", &v[i]);
	}
	for (int i = 0; i <= 100000; ++i){
		v1[i] = 0;
		v2[i] = 0;
	}

	for (int i = 0; i < n/2; ++i){
		v1[v[2*i]] += 1;
		v2[v[2*i+1]] += 1;
	}

	max1 = v1[1];
	max2 = v2[1];
	i1 = 1;
	i2 = 1;
	for (int i = 2; i <= 100000; ++i){
		if (max1 == v1[i]) {
			count1 +=1;
		}else if (max1 < v1[i]) {
			max1 = v1[i];
			i1 = i;
			count1 = 1;
		}
		if (max2 == v2[i]) {
			count2 +=1;
		}else if (max2 < v2[i]) {
			max2 = v2[i];
			i2 = i;
			count2 = 1;
		}
	}

	if ((i1!=i2) || (count1>1) || (count2>1)) {
		printf("%d\n", n-max1-max2);
	} else {
		v1[i1] = 0;
		v2[i2] = 0;
		max3 = v1[1];
		max4 = v2[1];

		i1 = 1;
		i2 = 1;
		for (int i = 2; i <= 100000; ++i){
			if (max3 < v1[i]) {
				max3 = v1[i];
				i1 = i;
			}
			if (max4 < v2[i]) {
				max4 = v2[i];
				i2 = i;
			}
		}
		if (max1+max4 >= max2+max3) {
			printf("%d\n", n-max1-max4);
		}else{
			printf("%d\n", n-max3-max2);
		}
	}
	return 0;
}