import pprint
import sys
import typing


class Loc(typing.NamedTuple):
    x: int
    y: int


def main() -> int:
    forest_frame = [list(line.strip()) for line in sys.stdin.readlines()]
    frame_width = len(forest_frame[0])
    frame_height = len(forest_frame)
    loc = Loc(x=0, y=0)

    trees_encountered = 0

    while loc.y <= (frame_height - 1):
        at_loc = forest_frame[loc.y][loc.x]
        if at_loc == "#":
            trees_encountered += 1

        next_x = (loc.x + 3) % frame_width
        next_y = loc.y + 1
        next_loc = Loc(x=next_x, y=next_y)
        loc = next_loc

    print(f"trees encountered: {trees_encountered}")
    return 0


if __name__ == "__main__":
    sys.exit(main())