FSM

public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        boolean[] sensors = new boolean[6];
        LFS state = LFS.STOP;
        String output = "";
        while (true) {
            String input = scan.nextLine();
            if (input.length() != 6) {
                break;
            }
            for (int i = 0; i < 6; i++) {
                if (input.charAt(i) == '1') {
                    sensors[i] = true;
                } else {
                    sensors[i] = false;
                }
            }
            switch (state) {
                case STOP:
                    if (sensors[2] || sensors[3]) {
                        state = LFS.FORWARD;
                    }
                    break;
                case FORWARD:
                    if (sensors[0] || sensors[1]) {
                        state = LFS.RIGHT;
                    } else if (sensors[4] || sensors[5]) {
                        state = LFS.LEFT;
                    } else if (sensors[0] && sensors[1] && sensors[2] && sensors[3] && sensors[4] && sensors[5]) {
                        state = LFS.STOP;
                    }
                    break;
                case RIGHT:
                    if ((!sensors[0] && !sensors[1]) && (sensors[3] || sensors[4] || sensors[5])) {
                        state = LFS.FORWARD;
                    }
                    break;
                case LEFT:
                    if ((!sensors[4] && !sensors[5]) && (sensors[0] || sensors[1] || sensors[2])) {
                        state = LFS.FORWARD;
                    }
                    break;
            }

            switch (state) {
                case STOP: System.out.println("stop"); break;
                case FORWARD: System.out.println("forward"); break;
                case RIGHT: System.out.println("right"); break;
                case LEFT: System.out.println("left"); break;
            }
        }

    }