import re

def find_all_digit_substrings(file_path):
    with open(file_path, 'r') as file:
        lines = file.readlines()
        for line in lines:
            digit_substrings = re.findall(r'\d+', line)
            if digit_substrings:
                print(' '.join(digit_substrings))

file_path = './simple.in'
find_all_digit_substrings(file_path)