n,k,t = map(int,input().split())
s = input()
tp = [[0] for _ in range(4)]
for p in range(n):
	for i in range(1,4):
		tp[i].append(tp[i][-1]+(int(s[p])==i))
		
		
def test(w,p):
	ss1 = tp[1][w+t-1] + (tp[1][-1]-tp[1][p-1])
	ss2 = tp[2][w+t-1]-tp[2][w-1] + tp[2][p+t-1]-tp[2][p-1]
	wg = w-1 + n-(p+t-1)
	s2 = tp[2][w-1] + tp[2][-1]-tp[2][p+t-1]
	return ss1,ss2,wg,s2

	
if k>=tp[1][-1]: #nie musi jechać do pracy
	print(n-max(n-tp[3][-1]-k,0))
else:
	ans = -1
	for w in range(1,n-2*t+2):
		for p in range(w+t,n-t+2):
			ss1,ss2,wg,s2 = test(w,p)
			if ss1+ss2>k: continue
			gp = wg-max(s2-(k-(ss1+ss2)),0)
			ans = max(ans,gp)
	print(ans)