from sys import stdin
from math import lcm

def tadd(a, b):
    return tuple(map(sum, zip(a, b)))

def tmul(a, b):
    return tuple([n*b for n in a])

def tmod(a, b):
    return tuple([a%b for (a,b) in zip(a, b)])

# direction tuple
def tdir(f):
    return ([0, 1, 0, -1][f%4], [-1, 0, 1, 0][f%4])

data = stdin.readlines()
start = (data[0].index('.') - 1, -1)
end = (data[-1].index('.') - 1, len(data) - 2)
data = [l.strip()[1:-1] for l in data[1:-1]]
w = len(data[0])
h = len(data)
cycle = lcm(w, h)

# 0 N  1 E  2 S  3 W
blizzards = [set() for _ in range(4)]
for y, line in enumerate(data):
    for x, c in enumerate(line):
        dirs = "^>v<"
        if c in dirs:
            blizzards[dirs.index(c)].add((x, y))

def coll(x, y, t):
    if (x, y) == start: return False
    if (x, y) == end: return False
    if not 0 <= x < w: return True
    if not 0 <= y < h: return True
    for d in range(4):
        v = tmod(tadd((x, y), tmul(tdir(d), -t)), (w, h))
        if v in blizzards[d]:
            return True
    return False

def search():
    cur = {(start, 0, 0)}
    frontier = set()
    visited = set(cur)
    while True:
        for bv, t, gid in cur:
            vs = [bv]
            for d in range(4):
                vs.append(tadd(bv, tdir(d)))
            for v in vs:
                if not coll(*v, t+1):
                    new = None
                    if v == end and gid == 0:
                        new = (v, t+1, 1)
                    elif v == start and gid == 1:
                        new = (v, t+1, 2)
                    elif v == end and gid == 2:
                        return t+1
                    else:
                        new = (v, t+1, gid)
                    chk = (new[0], new[1] % cycle, new[2])
                    if not chk in visited:
                        visited.add(chk)
                        frontier.add(new)
        cur = frontier
        frontier = set()
    return None

print(search())