A function runs three loops one after another: one over n, one over m, and another over n. Given n and m, return the total number of loop passes. When loops are sequentialSequential CodeStatements or loops that run one after another, not inside each other., their work adds up: n + m + n = 2n + m, which is O(n + m). Contrast this with nested loops, where counts multiply. Telling "one after another" from "one inside another" is most of the skill in reading complexity from code.