num = input()
k = int(input())

div3 = int(num) % 3 == 0

a2 = 0
a5 = 0

for c in num:
    if c in '2468':
        a2 += 1
    if c == '5':
        a5 += 1

pairs = (len(num)*(len(num) - 1)) / 2
ax = len(num) - a2 - a5

data = list()

data.append([0, 0, 0])

if num[-1] in '2468':
    data[0][1] = 1
elif num[-1] == '5':
    data[0][2] = 1
else:
    data[0][0] = 1

for i in range(k):

    data.append([data[i][0] * (1 - (a2 + a5)/pairs) + data[i][1] * (ax/pairs) + data[i][2] * (ax/pairs),
                data[i][0] * (a2/pairs) + data[i][1] * (1 - (ax + a5)/ pairs) + data[i][2] * (a2 / pairs),
                data[i][0] * (a5 / pairs) + data[i][1] * (a5 / pairs) + data[i][2] * (1 - (ax + a2)/ pairs)])

answer = data[k][2]

if (div3):
    answer += data[k][1]

print(answer)