hacker rank python (matrix script)

MATRIX SCRIPT

//HARDEST IN THE SOLUTIONS

import re

import sys

nm = input().split()

n = int(nm[0])

m = int(nm[1])

matrix = []

for _ in range(n):

    matrix_item = input()

    matrix.append(matrix_item)

string = ""      

for i in range(m):

    string += "".join(matrix[j][i] for j in range(n))

res = re.sub(r"(?<=\w)[!@#$%&\s]+(?=\w)",r" ",string)    

sys.stdout.write(res)