N, K = map(int, input().split())
S = input()
buy_flag_first = [0] * N
bonus = 0

for i in range(N):
    if bonus == 0:
        buy_flag_first[i] = 1
    else:
        bonus -= 1
    
    if S[i] == '1':
        bonus += 1
    elif S[i] == '2':
        bonus += 2

buy_flag_second = [0] * N

for i in range(N):
    if bonus == 0:
        buy_flag_second[i] = 1
    else:
        bonus -= 1
    
    if S[i] == '1':
        bonus += 1
    elif S[i] == '2':
        bonus += 2

for i in range(N):
    if bonus == 0:
        buy_flag_second[i] = 1
    else:
        bonus -= 1
    
    if S[i] == '1':
        bonus += 1
    elif S[i] == '2':
        bonus += 2

first = sum(buy_flag_first)
second = sum(buy_flag_second)

if K <= N:
    ans = sum(buy_flag_first[:K])
    print(ans)
else:
    shou, amari = K // N, K % N
    ans = first + second * (shou - 1) + sum(buy_flag_second[:amari])
    print(ans)