def solution(cards):
    cycle_length = [0, 0]
    group = [-1] * len(cards)
    for i in range(len(cards)):
        if group[i] != -1:
            continue
        curr = i
        count = 0
        while group[curr] == -1:
            group[curr] = i
            curr = cards[curr] - 1
            count += 1
        cycle_length = sorted(cycle_length + [count])[-2:]
    return cycle_length[0] * cycle_length[1]