def f(inp):
    def g(i, j, l):
        old_i, old_j = i, j
        visited.add((i, j))
        if (i, j)==end:
            paths.append(l)
        else:
            crossing = False
            deadend = False
            oi, oj = i, j
            while not (crossing or deadend or (i, j)==end):
                steps = []
                for di, dj in [(0, 1), (1, 0), (0, -1), (-1, 0)]:
                    if inp[i+di][j+dj] in '.v>':
                        steps.append((i+di, j+dj))
                if len(steps)>2:
                    crossing = True
                    continue
                if (oi, oj)!=steps[0]:
                    oi, oj = i, j
                    i, j = steps[0] 
                elif len(steps)==2:
                    oi, oj = i, j
                    i, j = steps[1]
                else:
                    deadend = True
                    continue
                l += 1
            if deadend:
                return
            elif (i, j)==end:
                g(i, j, l)                
            elif crossing and (i, j) not in visited:
                for di, dj in [(0, 1), (1, 0), (0, -1), (-1, 0)]:
                    if di==1 and inp[i+di][j+dj]=='v':
                        g(i+di, j+dj, l+1)
                    elif dj==1 and inp[i+di][j+dj]=='>':
                        g(i+di, j+dj, l+1)
        visited.remove((old_i, old_j))
    visited = set()
    paths = []
    inp = ['#'*len(inp[0])] + inp + ['#'*len(inp[0])]
    si = 1
    sj = inp[1].index('.')
    end = (len(inp)-2, inp[-2].index('.'))
    g(si, sj, 0)
    return sorted(paths, reverse=True)

inp = '''
#.#####################
#.......#########...###
#######.#########.#.###
###.....#.>.>.###.#.###
###v#####.#v#.###.#.###
###.>...#.#.#.....#...#
###v###.#.#.#########.#
###...#.#.#.......#...#
#####.#.#.#######.#.###
#.....#.#.#.......#...#
#.#####.#.#.#########v#
#.#...#...#...###...>.#
#.#.#v#######v###.###v#
#...#.>.#...>.>.#.###.#
#####v#.#.###v#.#.###.#
#.....#...#...#.#.#...#
#.#########.###.#.#.###
#...###...#...#...#.###
###.###.#.###v#####v###
#...#...#.#.>.>.#.>.###
#.###.###.#.###.#.#v###
#.....###...###...#...#
#####################.#
'''.strip().split('\n')

assert f(inp)==[94, 90, 86, 82, 82, 74]

inp = open('input.txt').read().strip().split('\n')
print(max(f(inp)))