program lcm;
var a,b,n:longint;
begin
    read(a,b);
    if a<=b then
       begin
             n:=0;
             while b mod a<>0 do
                 begin
                    n:=n+1;
                    a:=a+1;
                    b:=b+1;
                 end;
       end
    else
       begin
             n:=0;
             while a mod b<>0 do
                 begin
                    n:=n+1;
                    a:=a+1;
                    b:=b+1;
                 end;
       end;
    write(n);
end.