var       a: String;
    b, x, k: int64;
          i: Byte;

begin
 readln(a);
 readln(b);
 x := 0;
 k := 0;
 for i := 1 to length(a) do
  begin
    x := x * 10 + (ord(a[i]) - 48);
    if (x < b) and (k = 0) and (i > 1)
     then continue;
    k := 1;
    x := x mod b;
  end;
 writeln(x);
end.
