ABC classification for a Rotterdam warehouse

A distribution centre in Rotterdam stocks thousands of spare parts. Management applies ABC analysis (the Pareto idea): a few items carry most of the yearly value and deserve tight control.

Task: line 1 is the number of items n. Then n lines sku units cost_cents (sku is text without spaces, units and cost_cents are non-negative integers). The yearly value of an item is units * cost_cents. Sort the items by value descending, ties by sku ascending (plain string order). Walk down the sorted list keeping before, the total value of the items already passed. An item is class A if before is strictly less than 80% of the grand total, otherwise class B if before is strictly less than 95% of the grand total, otherwise class C. Compare using integers only (before * 100 < 80 * total). Print one line per item sku value class in the sorted order, then a final line A=x B=y C=z with the class counts.