from time import sleep

with open("input") as f:
    lights = [n.strip() for n in f.readlines()]

STEPS = 100
# STEPS = 4

X_MAX = len(lights)
Y_MAX = len(lights[0])


def print_lights():
    for row in lights:
        print(row)


def neighbors_that_are_on(center_x, center_y):
    count = 0
    for d_x in range(-1, 2):
        for d_y in range(-1, 2):
            x = center_x + d_x
            y = center_y + d_y
            if d_x == 0 and d_y == 0:
                continue
            if x < 0 or x >= X_MAX:
                continue
            if y < 0 or y >= Y_MAX:
                continue
            neighbor = lights[x][y]
            if neighbor == "#":
                count += 1
    return count


def get_next_state(prev_state, neighbors_count):
    if prev_state == "#":
        if neighbors_count in [2, 3]:
            return "#"
        else:
            return "."
    else:  # light == '.'
        if neighbors_count == 3:
            return "#"
        else:
            return "."


print("Initial state")
print_lights()
print()

for step in range(STEPS):
    new_lights = []

    for x in range(X_MAX):
        line = ""
        for y in range(Y_MAX):
            light = lights[x][y]
            neighbors_count = neighbors_that_are_on(x, y)
            next_state = get_next_state(light, neighbors_count)
            line += next_state
        new_lights.append(line)

    lights = new_lights
    print("Step", step + 1)
    print_lights()
    print()
    sleep(0.03)


count = 0
for line in lights:
    for light in line:
        if light == "#":
            count += 1

print(count)

# 353: too low