Операции числами в недесятичной системе счисления.

abc = [i for i in range(10)] + [chr(i) for i in range(ord('a'), ord('z')+1)]
 
FirstNumber = int(input())
SecondNumber = int(input())
Base = int(input())
 
assert(Base <= 36)
 
FirstDigits = []
SecondDigits = []
ThirdDigits = []
 
while FirstNumber > 0:
    FirstDigits.append(FirstNumber % Base)
    FirstNumber //= Base
 
for i in FirstDigits[::-1]:
    print(abc[i], end = '')
print()
 
while SecondNumber > 0:
    SecondDigits.append(SecondNumber % Base)
    SecondNumber //= Base
for i in SecondDigits[::-1]:
    print(abc[i], end = '')
print()
 
up = 0
maxlen = max(len(FirstDigits), len(SecondDigits))
 
for i in range(maxlen - len(FirstDigits)):
    FirstDigits.append(0)
 
for i in range(maxlen - len(SecondDigits)):
    SecondDigits.append(0)
 
for i in range(max(len(FirstDigits), len(SecondDigits))):
    tmp = FirstDigits[i] + SecondDigits[i] + up
    ThirdDigits.append (tmp % Base)
    up = tmp // Base
ThirdDigits.append(up)
 
for i in ThirdDigits[::-1]:
    print(abc[i], end = '')
print()

def toBASE(num, base):
    alpha = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ"
    b = alpha[num % base] 
    while num >= base :
        num = num // base
        b += alpha[num % base] 
    return b[::-1] 
 
FirstNumber = input()
SecondNumber = input()
Base = int(input())
 
# перевод в "10"
a = int(FirstNumber,Base)
b = int(SecondNumber,Base)
 
# операции с числами
res = a * b
 
# перевод обратно
res = toBASE(h,Base)
 
print(res)