cassettes = new Map([
[11,12,13,14,15,16,17,19,21,23,25],
[11,12,13,14,15,16,17,19,21,23,26],
[11,12,13,14,15,16,17,19,22,25,28],
[11,12,13,14,15,17,19,21,24,27,30],
[11,12,13,14,15,17,19,22,25,28,32],
].map(cassette => [`${cassette[0]}/${cassette[cassette.length - 1]}T`, cassette]))