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 Python (2.7.6) (judge verdict: Accepted)

#!/usr/bin/env python

from collections import deque
import itertools as it
import sys
import math

sys.setrecursionlimit(1000000)

INF = 10 ** 18

N = input()
v = map(int, raw_input().split())

cnt1 = [0] * 110000
cnt2 = [0] * 110000

for i in range(0, N, 2):
    cnt1[v[i]] += 1
    cnt2[v[i + 1]] += 1

v1, v2 = [], []
for i in range(110000):
    v1.append((cnt1[i], i))
    v2.append((cnt2[i], i))

v1.sort(reverse = True)
v2.sort(reverse = True)

if v1[0][1] != v2[0][1]:
    print N - v1[0][0] - v2[0][0]
else:
    print N - max(v1[1][0] + v2[0][0], v1[0][0] + v2[1][0])