text: Stores the characters which are not appearing in S
code: let V = [ ] ; for ( let i = ' ' . charCodeAt ( ) ; i < ( ' ' . charCodeAt ( ) + Math . min ( N , 25 ) ) ; ++ i ) { if ( M . has ( String . fromCharCode ( i ) ) == false ) { V . push ( String . fromCharCode ( i ) ) ; } }