#include <library.h>

/* a variation on the repetition theme allows convenient
   interactive testing */

void thing(const int N)
{ const int Q = N / 10,
            R = N % 10;
  print(R);
  if (Q > 0)
    thing(Q);
  print(R); }

void test_it()
{ print("type a number (or -1 to stop) ");
  const int x = read_int();
  if (x != -1)
  { thing(x);
    print("\n");
    test_it(); } }

void main()
{ test_it(); }