#!/usr/bin/env python3

input_num = 0b0

line0 = input().split()
line1 = input()


count=int(line0[0])
required_one=int(line0[1])

original_in = [int(i-48) for i in bytes(line1.encode('utf-8'))]


a = 0

r = 0
for k in original_in[::-1]:
    if int(k):
        r += 2**a
    a += 1

original_in = r


last_num = input_num

i = 0
while True:
    last_num += 1

    if last_num == 2 ** count - 1:
        break

    p = 0
    # print("{:b}".format(last_num))
    for z in "{:b}".format(last_num):
        if int(z):
            p += 1

    if p == required_one and last_num != original_in:
        i += 1


print(i)