LIMIT = (20, 20)

def solve():
    point = (0, 0)
    valid_paths = 0
    path = [point]
    tried_directions = {}
    solutions = []

    while True:
        # Display
        #print_map(point, path)
        #print 'PATH', path
        #print 'POINT', point
        #print 'DIRECTIONS', tried_directions.get(point)
        #print 
        #res = raw_input()
        #if res == 'd':
            #import pdb; pdb.set_trace()

        direction = tried_directions.get(point, -1) + 1
        if direction == 2:
            direction = None

        if direction is None:
            # If all moves from this place were tried
            if point == (0, 0):
                return valid_paths
            else:
                if point in tried_directions:
                    del tried_directions[point]
                path.pop()
                point = path[-1]
                continue
        else:
            tried_directions[point] = direction
            if direction == 0:
                target = (point[0] + 1, point[1])
            else:
                target = (point[0], point[1] + 1)

        if (target[0] < 0 or target[0] > LIMIT[0]
            or target[1] < 0 or target[1] > LIMIT[1]
            or target in path):
            # Outside exception or path crossing
            pass
        elif target == LIMIT:
            valid_paths += 1
        else:
            # If target is ok then
            # replace point with target and update path 
            point = target
            path.append(point)