you give string b consist lowercase letter in operation change character b lowercase letterYour goal satisfy follow conditionsevery letter strictly letter b alphabetEvery letter b strictly letter alphabetBoth b consist distinct letterreturn minimum number operation need achieve goal Example 1input aba b caaOutput 2explanation consider good way condition true1 Change b ccc 2 operation letter letter b2 Change bbb b aaa 3 operation letter b letter a3 Change aaa b aaa 2 operation b consist distinct letterthe good way 2 operation condition 1 condition 3example 2input dabadd b cdaoutput 3explanation the good way condition 1 true change b eee Constraints1 alength blength 105a b consist lowercase letter