var
  a,i,k,m,mm,n,sum,d : int64;
  s,t : string;
  err : integer;
begin
  assign(input,'SIMPLE.IN'); reset(input);
  assign(output,'SIMPLE.OUT'); rewrite(output);
  readln(a,k);
  while a>1 do
    begin
      s+=a mod k;
      a:=a div k;
    end;
    t:=s;
     val(t,n,err);
     mm:=n;
     while mm<>0 do begin
     d:=mm mod 10;
     sum:=sum+d;
     mm:=mm div 10;
     end;
     m:=1;
     while n<>0 do begin
       d:=n mod 10;
       m:=m*d;
       n:=n div 10;
     end;
     writeln(m-sum);
       close(input); close(output);
end.