ɾÊýÎÊÌ⣨dele£©

program dele;

const
 maxn=100;

var
 s,fin:ansistring;
 n:longint;
 st:array [-1..maxn] of longint;
 
procedure init;
begin
 readln(s);
 readln(n);
end;

procedure main;
var
 tot,i,finish,ed:longint;
 min:char;
begin
 fillchar(st,sizeof(st),0);
 i:=0;
 ed:=n+1;
 fin:='';
 finish:=0;
 while finish<length(s)-n do
  begin
   min:='z';
   for i:=st[finish-1]+1 to ed+finish do
    begin
     if s[i]<min then
      begin
       min:=s[i];
       st[finish]:=i;
      end;
    end;
   fin:=fin+min;
   inc(finish);
  end;
 while fin[1]='0' do delete(fin,1,1);
 writeln(fin);
end;

begin
 assign(input,'dele.in'); reset(input);
 assign(output,'dele.out'); rewrite(output);
 
 init;
 main;
 
 close(input); close(output);
end.