Totals By Category

Keep a running total per category. Input: the first line is a whole number n, followed by n pairs of lines, a category name and then an amount as a decimal number; read them with a bare input(), no prompts, using range(n). Use a dict of running sums: use in to check whether the category is already a key, adding the amount to its total if so and otherwise storing the amount as the first total. After the last pair, print one line per category in the order first seen, in the form <category>: <total> with the total to two decimals.