<gh_stars>0
def find_missing_letter(chars):
    for i in range(1, len(chars)):
        if not ord(chars[i]) == ord(chars[i - 1]) + 1:
            return chr(ord(chars[i]) - 1)

def find_missing_letter(chars):
    for i in range(1, len(chars)):
        if not ord(chars[i]) == ord(chars[i - 1]) + 1:
            return chr(ord(chars[i]) - 1)