from lib import get_data
from lib import Grid2D

data = get_data(__file__)

g = Grid2D(data)
seen = set()
for i in range(10**9):
    if g.hash() in seen:
        print(i)
        break

    seen.add(g.hash())
    blocked = set(g.find(">v"))
    for p in g.find(">"):
        np = (p[0], (p[1] + 1) % g.n_cols)
        if np in blocked:
            continue
        g[p] = "."
        g[np] = ">"

    blocked = set(g.find(">v"))
    for p in g.find("v"):
        np = ((p[0] + 1) % g.n_rows , p[1])
        if np in blocked:
            continue
        g[p] = "."
        g[np] = "v"