import numpy as np
import scipy as sp


trans = {">": 0, "<": 1, "v": 2, "^": 3}

with open("u") as fp:
    lines = fp.read().strip().split("\n")
    lines = lines[1:-1]
    ymax = len(lines)
    xmax = len(lines[0]) - 2
    winds = np.zeros((4, ymax, xmax), dtype=bool)
    for y, line in enumerate(lines):
        line = line.strip("#")
        for x, c in enumerate(line):
            if c in trans:
                winds[trans[c]][y][x] = 1


def rollwinds(winds):
    winds[0] = np.roll(winds[0], 1, axis=1)
    winds[1] = np.roll(winds[1], -1, axis=1)
    winds[2] = np.roll(winds[2], 1, axis=0)
    winds[3] = np.roll(winds[3], -1, axis=0)
    return winds


cross_kernel = np.array(
    [[0, 1, 0], [1, 1, 1], [0, 1, 0]],
    dtype=bool,
)

minute = 0
path = np.zeros((ymax, xmax), dtype=bool)
while path[-1][-1] == False:  # as long as next isnt last minute
    minute += 1
    winds = rollwinds(winds)
    # just dilate all the possible positions
    path = sp.ndimage.binary_dilation(
        path,
        cross_kernel,
    )
    path[0][0] = True  # could have always waited (always seed start)
    save_positions = np.any(winds, axis=0)
    path = np.bitwise_and(path, np.invert(save_positions))

path = np.zeros((ymax, xmax), dtype=bool)
while path[0][0] == False:
    minute += 1
    winds = rollwinds(winds)
    path = sp.ndimage.binary_dilation(
        path,
        cross_kernel,
    )
    path[-1][-1] = True
    save_positions = np.invert(np.any(winds, axis=0))
    path = np.bitwise_and(path, save_positions)

path = np.zeros((ymax, xmax), dtype=bool)
while path[-1][-1] == False:
    minute += 1
    winds = rollwinds(winds)
    path = sp.ndimage.binary_dilation(
        path,
        cross_kernel,
    )
    path[0][0] = True
    save_positions = np.any(winds, axis=0)
    path = np.bitwise_and(path, np.invert(save_positions))

print(minute + 1)