var
 i: integer
 s: string;
begin
 s := '$' + ThatHexString;
 i := StrToInt(a);
end;

const HEX: array['A'..'F'] of INTEGER = (10, 11, 12, 13, 14, 15);
var str: string;
  Int, i: integer;
begin
 READLN(str);
 Int := 0;
 for i := 1 to Length(str) do
  if str[i] < 'A' then
  Int := Int * 16 + ORD(str[i]) - 48
  else
  Int := Int * 16 + HEX[str[i]];
 WRITELN(Int);
 READLN;
end.