//infoarena next
const nrcif = 1000000;
type nrmare = array[0..nrcif] of integer;
     nrmic = array[0..100] of integer;

var n:nrmare;
    aux:nrmic;
    d:int64;
    s:ansistring;
    lungn,lungaux:longint;

procedure strtonr(var s:ansistring);
var i:longint;
    coda:integer;
begin
lungn:=length(s); coda:=ord('0');
for i:=length(s) downto 1 do
        n[lungn-i+1]:=ord(s[i])-coda;
end;

procedure strtonrmic(var s:ansistring);
var i:longint;
    coda:integer;
begin
lungaux:=length(s); coda:=ord('0');
for i:=length(s) downto 1 do
        aux[lungaux-i+1]:=ord(s[i])-coda;
end;


procedure citire;
begin
assign(input,'next.in'); reset(input);
readln(s); strtonr(s); s:='';
readln(d);
closE(input);
end;

procedure suma(var b:nrmic);
var i:longint;
     t:int64;
begin

i:=1;
t:=0;

while (i<=lungn) or (i<=lungaux) or (t <>0 )  do
      begin
      t:=t div 10;
      t:=t+n[i];
      if i < 100 then t:=t+b[i];
      n[i]:=t mod 10;
      i:=i+1;
      end;
lungn:=i-2;
end;

function rest(p:int64):int64;
var i:longint;
    t:int64;
begin
i:=lungn;
t:=0;
while i > 0 do
        begin
        t:=(t * 10 + n[i]) mod p;
        dec(i);
        end;
rest:=t;
end;

procedure afis;
var i:longint;
begin
assign(output,'next.out'); rewrite(output);
for i:=lungn downto 1 do
        write(n[i]);
close(output);
end;

procedure calc;
var rr,rez:int64;
    ss:ansistring;
begin
rr:=rest(d);
rez:=(d-rr) mod d;
str(rez,ss);
fillchar(aux,sizeof(aux),0);
strtonrmic(ss);
suma(aux);
afis;
end;

begin
citire;
calc;
end.