HackerRank Python - Matrix Script

#!/bin/python3

import math
import os
import random
import re
import sys



first_multiple_input = input().rstrip().split()

n = int(first_multiple_input[0])

m = int(first_multiple_input[1])

matrix = []

for _ in range(n):
    matrix_item = input()
    matrix.append(matrix_item)

decoded_message = ""
for column in range(m):
    for row in range(n):
        decoded_message += matrix[row][column]        

print(re.sub(r"(?<=\w)([^\w]+)(?=\w)", " ", decoded_message))