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

# 一箱目
atari = 0
buy = 0
first_box_cnt = []
for ice in S:
    if atari > 0:
        atari -= 1
    else:
        buy += 1

    if ice == '1':
        atari += 1
    elif ice == '2':
        atari += 2
    first_box_cnt.append(buy)

# 二箱目
buy = 0
second_box_cnt = []
for ice in S:
    if atari > 0:
        atari -= 1
    else:
        buy += 1

    if ice == '1':
        atari += 1
    elif ice == '2':
        atari += 2
    second_box_cnt.append(buy)

# Kの大きさで場合分け
if K <= N:
    print(first_box_cnt[K-1])
elif N < K:
    box_cnt = K // N
    res = first_box_cnt[-1]
    res += second_box_cnt[-1] * (box_cnt - 1)
    if K % N != 0:
        res += second_box_cnt[(K % N) - 1]

    print(res)