#!/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)

sentence = ""

for j in range(m):
    for i in range(n):
        sentence += matrix[i][j]

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