By leading with a 5 the first player can always
plays another 5, you play a 2 and score 12.
Then as often as he plays a
you play a 2, and if at any stage he drops out of the series, 3, 10,
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,
worth the reader's study.