import operator
from functools import reduce

items = (int(x.strip()) for x in open("input.txt"))
values = {(2020, 3)}
tree = dict()


def tree_up(idx, step=1, offset=0):
    nxt = tree[(idx, step)] if (idx, step) in tree else None
    appendix = [] if nxt is None else tree_up(nxt+idx, step=step+1, offset=idx)
    return [idx-offset] + appendix


def prod(iterable):
    return reduce(operator.mul, iterable, 1)


for item in items:
    tmp_values = set(values)
    for elem in values:
        new = (elem[0] - item, elem[1]-1)
        if new == (0, 0):
            vals = tree_up(item)
            print(prod(vals))
        elif new[0] > 0 and new[1] > 0:
            if new not in tree:
                tree[new] = item
            tmp_values.add(new)
    values = tmp_values