Next int (0 to quit)? 42
Next int (0 to quit)? 9
Next int (0 to quit)? 18
Next int (0 to quit)? 55
Next int (0 to quit)? 7
Next int (0 to quit)? 108
Next int (0 to quit)? 4
Next int (0 to quit)? 70
Next int (0 to quit)? 203
Next int (0 to quit)? 15
Next int (0 to quit)? 0

Tree Structure:
            203
        108
            70
    55
42
        18
            15
    9
        7
            4
Sorted list:
4 7 9 15 18 42 55 70 108 203