['5', '10']
[['5', '10']]
['5', '30']
[['5', '10'], ['5', '30']]
['15', '30']
[['5', '10'], ['5', '30'], ['15', '30']]
['15', '10']
[['5', '10'], ['5', '30'], ['15', '30'], ['15', '10']]