you give integer k string s consist character lowercase latin letter asteriskeach asterisk replace 0 k inclusive lowercase Latin letter b different asterisk replace different count letter bThe result replacement call BAstringTwo string b different different length exist position a_i neq b_iA stre lexicographically small string b follow hold prefix b ne b position b differ string letter appear early alphabet corresponding letter b now consider different BAstrings find xth lexicographically smallest