By leading with a 5 the first player can always win. If your opponent
plays another 5, you play a 2 and score 12. Then as often as he plays a 5
you play a 2, and if at any stage he drops out of the series, 3, 10, 17,
24, 31, you step in and win. If after your lead of 5 he plays anything
but another 5, you make 10 or 17 and win. The first player may also win
by leading a 1 or a 2, but the play is complicated. It is, however, well
worth the reader's study.