from itertools import permutations
from operator import add



def construct(pieces):
	''' returns a list of heights of pieces '''
    x = []
    x.extend(e for y in pieces[:-1] for e in y[:-1])
    return x + pieces[-1]

def broken_window(pieces):
    amount = set(range(len(pieces)))
    for case in range(1, len(pieces)): # divide a pieces on two parts. In first part will be `case` pieces
        for part1 in permutations(amount, case): # Ok. first part is done
            first_part = construct([pieces[i] for i in part1]) # Now I build a heights of pieces from first part
            for part2 in permutations(amount - set(part1)): # Ok. second part is done
                second_part = construct([pieces[j][::-1] for j in part2]) # Now I build a heights of pieces from second part
                if len(first_part) != len(second_part): # If lengths not equals, continue 
                    continue
                if len(set(map(add, first_part, second_part))) == 1: # If I add i paices and get the same height -> all good -> return two parts
                    return list(part2), list(part1)