function lineUp(commands) {
    let position = 'F', counter = 0;
    for (let command of commands) {
        switch (command) {
            case 'L':
                switch (position) {
                    case 'F':
                        position = 'L';
                        break;
                    case 'L':
                        position = 'B';
                        break;
                    case 'B':
                        position = 'R';
                        break;
                    case 'R':
                        position = 'F';
                        break;
                }
                break;
            case 'R':
                switch (position) {
                    case 'F':
                        position = 'R';
                        break;
                    case 'L':
                        position = 'F';
                        break;
                    case 'B':
                        position = 'L';
                        break;
                    case 'R':
                        position = 'B';
                        break;
                }
                break;
            case 'A':
                switch (position) {
                    case 'F':
                        position = 'B';
                        break;
                    case 'L':
                        position = 'R';
                        break;
                    case 'B':
                        position = 'F';
                        break;
                    case 'R':
                        position = 'L';
                        break;
                }
                break;
        }
        if (position === 'F' || position === 'B') {
            counter++;
        }
    }
    return counter;
}