import hashlib
from collections import deque
from lib import add2


def solve():
    part_1 = False
    DIRS = [("U", (-1, 0)), ("D", (1, 0)), ("L", (0, -1)), ("R", (0, 1))]
    with open("i17.txt") as f:
        passcode = f.read().strip()

    maxlen = 0
    poss = deque([((0, 0), f"{passcode}")])
    while poss:
        if part_1:
            pos, path = poss.popleft()
        else:
            pos, path = poss.pop()

        if pos == (3, 3):
            if part_1:
                print(path[len(passcode):])
                return
            else:
                l = len(path) - len(passcode)
                if l > maxlen:
                    maxlen = l
        else:
            status = hashlib.md5(f"{path}".encode()).hexdigest()
            for (c, d), s in zip(DIRS, status[:4]):
                if s in "bcdef":
                    npos = add2(pos, d)
                    npath = path + c
                    if npos[0] >= 0 and npos[0] < 4 and npos[1] >= 0 and npos[1] < 4:
                        poss.append((npos, npath))
    print(maxlen)


if __name__ == "__main__":
    solve()