#!/bin/python3

import re

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 = ""

for m in range(M):
    for n in range(N):
        decoded +=matrix[n][m]

clean = re.sub(r'(?<=[A-Za-z0-9])[^A-Za-z0-9]+(?=[A-Za-z0-9])', ' ', decoded)

print(clean)