Input (grade 13): They have three pairs of true legs on the three thoracic segments, up to four pairs of prolegs on the middle segments of the abdomen, and often a single pair of prolegs on the last abdominal segment.
Output (grade 9): Caterpillars usually have three pairs of small, but noticeable, true legs at the front and up to 5 pairs of fleshy false legs at the back.