def run_by(right, down):
    trees = 0
    print((right, down))
    with open("3.txt") as f:
        idx = 0
        for i, line in enumerate(f):
            line = line.strip()

            l = list(line)
            c = line[idx % len(line)]
            if i % down == 0:
                l[idx % len(l)] = "X" if c == "#" else "O"
            print(f"{idx}\t{len(line)}\t{''.join(l)}\t{line}")

            if i % down == 0:
                idx += right
            if i == 0: continue

            if i % down == 0:
                if c == "#":
                    trees += 1
    print()
    return trees

s = [
        run_by(1, 1),
        run_by(3, 1),
        run_by(5, 1),
        run_by(7, 1),
        run_by(1, 2),
        ]
print(s)

import math
print(math.prod(s))