Decompress Encoded String

You are given an encoded string s. The encoding rule is as follows: a positive integer k followed by a lowercase English character c indicates that c should be repeated k times. Your task is to decompress the entire string. The input string s will always be valid, consisting of alternating positive integer counts and single lowercase English characters (e.g., 3a2b, 10z). There will be no standalone characters without a preceding count, and no nested compression. Counts will always be positive integers.