//infoarena next
const nrcif = 100000;
type nrmare = array[0..nrcif] of integer;

var n:nrmare;
    d:int64;
    s:ansistring;

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

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

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

i:=1;
t:=0;

while (i<=a[0]) or (i<=b[0]) or (t <>0 )  do
      begin
      t:=t div 10;
      t:=t+a[i]+b[i];
      a[i]:=t mod 10;
      i:=i+1;
      end;
a[0]:=i-2;
end;

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

procedure afis;
var i:longint;
begin
assign(output,'next.out'); rewrite(output);
for i:=n[0] downto 1 do
        write(n[i]);
close(output);
end;

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

begin
citire;
calc;
end.