matrix_script.py

#!/bin/python3

import re
n,m = map(int,input().split())
matrix = []
s = ''
for line in range(n):
    matrix.append(input()+' ')
s = ''.join(matrix[i][j] for j in range(m) for i in range(n))
s1 = re.sub(r'(?<=[a-zA-Z0-9])[^a-zA-Z0-9]+(?=[a-zA-Z0-9])',' ',s)
print(s1)