#!/usr/bin/env python3
"""Sorts all even integers in a list and leaves all odd integers in place.

The program prompts the user to enter a sequence of integers. It then
sorts all even integers in the sequence and leaves all odd integers
in their original position, and prints out the sorted sequence,
elements separated by spaces.
"""

import sys

__author__ = "Alan Mao and Patrick Duhanxhiu"
__copyright__ = "Copyright (c) 2016, Alan Mao and Patrick Duhanxhiu"


def merge_sort(nums, start, end):
    if start < end:
        middle = (start + end) // 2
        merge_sort(nums, start, middle)
        merge_sort(nums, middle + 1, end)
        merge(nums, start, middle, end)


def merge(nums, start, middle, end):
    list1 = nums[start:middle + 1]
    list2 = nums[middle + 1:end + 1]
    list1.append(sys.maxsize)
    list2.append(sys.maxsize)
    index1 = 0
    index2 = 0
    for index in range(start, end + 1):
        if list1[index1] <= list2[index2]:
            nums[index] = list1[index1]
            index1 += 1
        else:
            assert list1[index1] > list2[index2]
            nums[index] = list2[index2]
            index2 += 1


def file_init(nums):
    file_name = input('Enter the file name: ')
    try:
        file = open(file_name)
    except OSError:
        print('Error: the file specified cannot be opened')
        sys.exit(0)
    for line in file:
        for token in line.split():
            nums.append(int(token))


def stdin_init(nums):
    try:
        for k in input('Enter a sequence of integers: ').split():
            nums.append(int(k))
    except (TypeError, ValueError):
        print('Please enter a sequence of integers. ')
        stdin_init(nums)


ints = []
while True:
    input_method = input('Read the input from a file or from the standard input? ')
    if input_method == 'File':
        file_init(ints)
        break
    elif input_method == 'Standard input':
        stdin_init(ints)
        break
    else:
        print('Please enter "File" or "Standard input" to continue.')

even_ints = [x for x in ints if x % 2 == 0]
for i in range(len(ints)):
    if ints[i] % 2 == 0:
        ints[i] = None
merge_sort(even_ints, 0, len(even_ints) - 1)
j = 0
for i in range(len(ints)):
    if ints[i] is None:
        ints[i] = even_ints[j]
        j += 1
print(' '.join([str(x) for x in ints]))