Buggy python submission (verdict: Time Limit Exceeded):
n = int(input())
vec = list(map(int, input().split()))

odd = [vec[i] for i in range(0, n, 2)]
odd = [(n, odd.count(n)) for n in set(odd)]
odd.sort(key=lambda tpl: tpl[1], reverse=True)

even = [vec[i] for i in range(1, n, 2)]
even = [(n, even.count(n)) for n in set(even)]
even.sort(key=lambda tpl: tpl[1], reverse=True)

if odd[0][0] == even[0][0]:
    if odd[0][1] > even[0][1]:
        print(
            sum([cnt for _, cnt in odd[1:]]) + even[0][1] +
            sum([cnt for _, cnt in even[2:]]))
    else:
        print(
            sum([cnt for _, cnt in even[1:]]) + odd[0][1] +
            sum([cnt for _, cnt in odd[2:]]))
else:
    print(sum([cnt for _, cnt in odd[1:]]) + sum([cnt for _, cnt in even[1:]]))


Fixed submission:
from collections import defaultdict

n = int(input())
numbers = list(map(int, input().split()))

evens = defaultdict(lambda: 0)
odds = defaultdict(lambda: 0)
for i in range(0, n, 2):
    evens[numbers[i]] += 1
    odds[numbers[i + 1]] += 1

evens = list(evens.items())
odds = list(odds.items())

evens.sort(key=lambda pair: pair[1], reverse=True)
odds.sort(key=lambda pair: pair[1], reverse=True)

if len(evens) == 1 and len(odds) == 1:
    if evens[0][0] == odds[0][0]:
        print(n // 2)
    else:
        print(0)
    exit()

if len(evens) == 1 or len(odds) == 1:
    pairs = evens if len(evens) > len(odds) else odds
    if evens[0][0] == odds[0][0]:
        del pairs[1]
    else:
        del pairs[0]
    print(sum([v for _, v in pairs]))
    exit()

if evens[0][0] == odds[0][0]:
    if evens[0][1] == odds[0][1]:
        if evens[1][1] > odds[1][1]:
            del evens[1]
            del odds[0]
        else:
            del evens[0]
            del odds[1]
    elif evens[0][1] > odds[0][1]:
        del evens[0]
        del odds[1]
    else:
        del evens[1]
        del odds[0]
else:
    del evens[0]
    del odds[0]
print(sum([v for _, v in evens]) + sum([v for _, v in odds]))

Buggy python submission (verdict: Time Limit Exceeded):
n = int(input())
vec = list(map(int, input().split()))

odd = [vec[i] for i in range(0, n, 2)]
odd = [(n, odd.count(n)) for n in set(odd)]
odd.sort(key=lambda tpl: tpl[1], reverse=True)

even = [vec[i] for i in range(1, n, 2)]
even = [(n, even.count(n)) for n in set(even)]
even.sort(key=lambda tpl: tpl[1], reverse=True)

if odd[0][0] == even[0][0]:
    if odd[0][1] > even[0][1]:
        print(
            sum([cnt for _, cnt in odd[1:]]) + even[0][1] +
            sum([cnt for _, cnt in even[2:]]))
    else:
        print(
            sum([cnt for _, cnt in even[1:]]) + odd[0][1] +
            sum([cnt for _, cnt in odd[2:]]))
else:
    print(sum([cnt for _, cnt in odd[1:]]) + sum([cnt for _, cnt in even[1:]]))


Fixed submission:
from collections import defaultdict

n = int(input())
numbers = list(map(int, input().split()))

evens = defaultdict(lambda: 0)
odds = defaultdict(lambda: 0)
for i in range(0, n, 2):
    evens[numbers[i]] += 1
    odds[numbers[i + 1]] += 1

evens = list(evens.items())
odds = list(odds.items())

evens.sort(key=lambda pair: pair[1], reverse=True)
odds.sort(key=lambda pair: pair[1], reverse=True)

if len(evens) == 1 and len(odds) == 1:
    if evens[0][0] == odds[0][0]:
        print(n // 2)
    else:
        print(0)
    exit()

if len(evens) == 1 or len(odds) == 1:
    pairs = evens if len(evens) > len(odds) else odds
    if evens[0][0] == odds[0][0]:
        del pairs[1]
    else:
        del pairs[0]
    print(sum([v for _, v in pairs]))
    exit()

if evens[0][0] == odds[0][0]:
    if evens[0][1] == odds[0][1]:
        if evens[1][1] > odds[1][1]:
            del evens[1]
            del odds[0]
        else:
            del evens[0]
            del odds[1]
    elif evens[0][1] > odds[0][1]:
        del evens[0]
        del odds[1]
    else:
        del evens[1]
        del odds[0]
else:
    del evens[0]
    del odds[0]
print(sum([v for _, v in evens]) + sum([v for _, v in odds]))