N, K = [int(i) for i in input().strip().split(" ")]
S = [int(i) for i in input().strip()]

def buy(N,K,S):
    total = sum(S)
    atari = 0
    bought = 0
    for idx,i in enumerate(S):
        if idx >= K:
            return bought
        if atari == 0:
            bought += 1
        else:
            atari -= 1
        atari += i
    K -= len(S)
    if len(S) < total:
        return bought
    bought += (K//len(S)) * (len(S)-total)
    K %= len(S)
    for i in range(K):
        if atari == 0:
            bought += 1
        else:
            atari -= 1
        atari += S[i]
    return bought

print(buy(N,K,S))