def simulate(k):
    buy = 0
    s = 0, 0
    for _ in range(k):
        if s[1] == INF: break

        if s[1] == 0:
            buy += 1
        s = f(s)

    return buy


def f(s):
    p, t = s
    np = (p+1) % N

    if 0 < memo[p] <= t or memo[p] == INF:
        memo[p] = INF
        return np, INF

    nt = t + ds[p]
    if t > 0:
        nt -= 1

    memo[p] = nt
    return np, nt



INF = 1 << 60
N, K = map(int, input().split())
S = input()

memo = [0] * N
ds = [int(c) for c in S]

res = simulate(K)
print(res)