Mathison and pangrams

Mathison recently inherited an ancient papyrus that contained some text. Unfortunately, the text was not a pangram (a string using every letter of the Latin alphabet at least once). Now, Mathison has a particular liking for holoalphabetic strings and the text bothers him. The good news is that Mathison can buy letters from the local store in order to turn his text into a pangram. However, each le