Buggy python submission (verdict: Runtime Error):
import math
import itertools

n = int(input())
k = int(input())

if (n < 99 and k == 3) or (n < 9 and k == 2):
    print(0) 

else:
    f = len(str(n))

    #f-1桁以内に収まる数

    en = 1
    for i in range(k):
        en *= f-1-i

    de = math.factorial(k)


    s = en // de * pow(9, k)

    #print(s)
    #f桁目によって絞る

    kami = int(str(n)[0])

    en_2 = 1
    for i in range(k-1):
        en_2 *= f-1-i

    de_2 = math.factorial(k-1)


    s += (en_2 // de_2 * pow(9, k-1)) * (kami-1)


    #以下上1桁は同じ数字

    keta = list(range(f-1))
    num = list(range(1,10))

    b =  kami * pow(10, f-1)
    m = 0

    if k == 1:
        s += 1
    elif k == 2:
        s += 9*(f-2) + int(str(n)[1])
    else:
        kami2 = int(str(n)[1])

        en_3 = (f-2)*(f-3)

        de_3 = 2


        s += (en_3 // de_3 * pow(9, k-1))  + kami2 * 9 * (f-2)

    print(s)

Fixed submission:
import math
import itertools

n = int(input())
k = int(input())

f = len(str(n))

if f < k:
    print(0)
else:
    #f-1桁以内に収まる数

    en = 1
    for i in range(k):
        en *= f-1-i

    de = math.factorial(k)


    s = en // de * pow(9, k)


    #f桁目によって絞る

    kami = int(str(n)[0])

    en = 1
    for i in range(k-1):
        en *= f-1-i

    de = math.factorial(k-1)


    s += (en // de * pow(9, k-1)) * (kami-1)


    #以下上1桁は同じ数字

    keta = list(range(f-1))
    num = list(range(1,10))

    b =  kami * pow(10, f-1)
    m = 0


    if k == 1:
        m = b
        if m <= n:
            s += 1
    else:
        for d in itertools.product(num, repeat=k-1):
            for c in itertools.combinations(keta, k-1):
                m = b
                for i in range(k-1):
                    m +=  d[i] * pow(10, c[i])
                if m <= n:
                    s += 1

    print(s)

Buggy python submission (verdict: Runtime Error):
import math
import itertools

n = int(input())
k = int(input())

f = len(str(n))

#f-1桁以内に収まる数

en = 1
for i in range(k):
    en *= f-1-i

de = math.factorial(k)


s = en // de * pow(9, k)

#print(s)
#f桁目によって絞る

kami = int(str(n)[0])

en_2 = 1
for i in range(k-1):
    en_2 *= f-1-i

de_2 = math.factorial(k-1)


s += (en_2 // de_2 * pow(9, k-1)) * (kami-1)


#以下上1桁は同じ数字

keta = list(range(f-1))
num = list(range(1,10))

b =  kami * pow(10, f-1)
m = 0

if k == 1:
    s += 1
elif k == 2:
    s += 9*(f-2) + int(str(n)[1])
else:
    kami2 = int(str(n)[1])

    en_3 = (f-2)*(f-3)

    de_3 = 2


    s += (en_3 // de_3 * pow(9, k-1))  + kami2 * 9 * (f-2)

print(s)

Fixed submission:
import math
import itertools

n = int(input())
k = int(input())

f = len(str(n))

if f < k:
    print(0)
else:
    #f-1桁以内に収まる数

    en = 1
    for i in range(k):
        en *= f-1-i

    de = math.factorial(k)


    s = en // de * pow(9, k)


    #f桁目によって絞る

    kami = int(str(n)[0])

    en = 1
    for i in range(k-1):
        en *= f-1-i

    de = math.factorial(k-1)


    s += (en // de * pow(9, k-1)) * (kami-1)


    #以下上1桁は同じ数字

    keta = list(range(f-1))
    num = list(range(1,10))

    b =  kami * pow(10, f-1)
    m = 0


    if k == 1:
        m = b
        if m <= n:
            s += 1
    else:
        for d in itertools.product(num, repeat=k-1):
            for c in itertools.combinations(keta, k-1):
                m = b
                for i in range(k-1):
                    m +=  d[i] * pow(10, c[i])
                if m <= n:
                    s += 1

    print(s)