def buy_box(ice_box, buy=0, hit=0): for ice in ice_box: if hit>0:hit-=1 else:buy+=1 hit+=ice return buy,hit def main(): box_len,full,ice_box = map(int,input().split()) ice_box=[int(i) for i in input()] if box_len>=full:print(buy_box(ice_box[:full])[0]) else: buy,hit=buy_box(ice_box) if hit>=box_len:print(buy) else:print(buy+buy_box(ice_box,hit=hit)[0]*(full//box_len-1)+buy_box(ice_box[:full%box_len],hit=hit)[0]) main()