TRS:
 {         times(x, y) -> help(x, y, 0()),
         help(x, y, c) -> if(lt(c, y), x, y, c),
   if(true(), x, y, c) -> plus(x, help(x, y, s(c))),
  if(false(), x, y, c) -> 0(),
         lt(0(), s(x)) -> true(),
         lt(s(x), 0()) -> false(),
        lt(s(x), s(y)) -> lt(x, y),
          plus(x, 0()) -> x,
          plus(0(), x) -> x,
         plus(x, s(y)) -> s(plus(x, y)),
         plus(s(x), y) -> s(plus(x, y))}
 Fail