from random import *
def generate():
    seed(62738493)
    S = ""
    for i in range(100000):
        S += chr(randint(48, 90))
    return S
S = generate()
S = list(S)
l = [] # here we keep the digits.
al = [] # here we keep the final numbers.
ts = '' # a sort of buffer for keeping numbers extracted from l before putting them into al.
for i in S:
    if i.isdigit():
      l.append(i)
    else:
        if l[-1] != '': #replace any non-digit character with a blank, but we don't want multiple blanks in a row. For some reaon, this line give an IndexError, says -1 is out of range.
            l.append('')