n,k=map(int,input().split())
L=[int(i) for i in list(input())]

def t(x):
	a=b=0
	for i in range(x):
		if a>0:a-=1
		else:b+=1
		a+=L[i%n]
	return(a,b)

if k<n:y=t(k)[1]
else:
	p,q=t(n)
	if p>0:y=q
	else:y=q*k//n+t(k%n)
	
print(y)