answer = ''

def checkio(teleports_string):
    path = []
    done = []
    graph(path, done, teleports_string.split(','), first='1')
    return answer


def graph(path, done, teleports, first):
    global answer
    path.append(first)
    if set(path) == {'1', '2', '3', '4', '5', '6', '7', '8'} and path[0] == '1' and path[-1] == '1':
        answer = ''.join([x for x in path])
    for i in range(len(teleports)):
        if first in teleports[i] and teleports[i] not in done:
            old_first = first
            pathdone = [len(path), len(done)]
            done.append(teleports[i])
            first = [x for x in teleports[i] if x != first][0]
            graph(path, done, teleports, first)
            done = done[:pathdone[1]]
            path = path[:pathdone[0]]
            first = old_first


#This part is using only for self-testing
if __name__ == "__main__":
    def check_solution(func, teleports_str):
        route = func(teleports_str)
        teleports_map = [tuple(sorted([int(x), int(y)])) for x, y in teleports_str.split(",")]
        if route[0] != '1' or route[-1] != '1':
            print("The path must start and end at 1")
            return False
        ch_route = route[0]
        for i in range(len(route) - 1):
            teleport = tuple(sorted([int(route[i]), int(route[i + 1])]))
            if not teleport in teleports_map:
                print("No way from {0} to {1}".format(route[i], route[i + 1]))
                return False
            teleports_map.remove(teleport)
            ch_route += route[i + 1]
        for s in range(1, 9):
            if not str(s) in ch_route:
                print("You forgot about {0}".format(s))
                return False
        return True

    assert check_solution(checkio, "12,23,34,45,56,67,78,81"), "First"
    assert check_solution(checkio, "12,28,87,71,13,14,34,35,45,46,63,65"), "Second"
    assert check_solution(checkio, "12,15,16,23,24,28,83,85,86,87,71,74,56"), "Third"
    assert check_solution(checkio, "13,14,23,25,34,35,47,56,58,76,68"), "Fourth"