def f(inp):
    def g(i, j, oi, oj, l):
        crossing = False
        deadend = False
        while not (crossing or deadend):
            steps = []
            for di, dj in [(0, 1), (1, 0), (0, -1), (-1, 0)]:
                if inp[i+di][j+dj]=='.':
                    steps.append((i+di, j+dj))
            if len(steps)>2:
                crossing = True
                continue
            elif len(steps)==1:
                deadend = True
                continue
            else:
                if (oi, oj)!=steps[0]:
                    oi, oj = i, j
                    i, j = steps[0] 
                else:
                    oi, oj = i, j
                    i, j = steps[1]
            l += 1
        if deadend and (i, j)==end:
            paths.append(l)
            print(l)
        elif deadend:
            pass
        elif crossing and (i, j) not in visited:
            visited.add((i, j))
            for di, dj in [(0, 1), (1, 0), (0, -1), (-1, 0)]:
                if inp[i+di][j+dj]=='.':
                    g(i+di, j+dj, i, j, l+1)
            visited.remove((i, j))
    visited = set()
    paths = []
    inp = [x.replace('>', '.').replace('v', '.') for x in inp]
    inp = ['#'*len(inp[0])] + inp + ['#'*len(inp[0])]
    si = 1
    sj = inp[1].index('.')
    end = (len(inp)-2, inp[-2].index('.'))
    g(si+1, sj, si, sj, 1)
    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]
#assert max(f(inp))==154

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