4. There are 85 pebbles on the table, Shu Ke and Bei Ta take turns to take pebbles, each person can only take 2, 4, 5, 7 pebbles or all at a time, and the one who takes the last pebble loses. Shu Ke goes first, his winning strategy is to take $\qquad$ pebbles the first time.
$2$