import functools

slope_map = []

with open('day3/input') as reader:
    slope_map.extend(reader.read().splitlines())


def check_slope(right, down):
    global slope_map
    pos = 0
    y = 1
    trees = 0
    for l in slope_map[1:]:
        if y % down == 0:
            pos = (pos + right) % len(l)
            if l[pos] == '#':
                trees += 1
        y += 1

    return trees


def check_slope_short(right, down):
    global slope_map
    trees = 0
    for (i, l) in enumerate(slope_map):
        if i % down == 0:
            pos = (i // down * right) % len(l)
            if l[pos] == '#':
                trees += 1

    return trees


def check_slope_even_short(right, down):
    global slope_map
    return len(list(filter(lambda b: b, map(lambda en: en[1][(en[0] // down * right) % len(en[1])] == '#', filter(lambda en: en[0] % down == 0, enumerate(slope_map))))))

slopes = [(1, 1), (3, 1), (5, 1), (7, 1), (1, 2)]

total_trees = functools.reduce(lambda prev, slope: prev * check_slope_even_short(*slope), slopes, 1)

print(total_trees)