#!/usr/bin/env python3

import sys

filename = sys.argv[1]
emails = []
passwords = []
tmp = 1
 
for line in open(filename):
    if line.strip():
        emails.append(line.strip()) if tmp % 2 == 1 else passwords.append(line.strip())
        tmp += 1
            
for i in range(len(emails)):
    temp = emails[i] + ':' + passwords[i]
    print(temp, file = open("out.txt", "a"))

lala@mail.ru
password1

coco@mail.ru
password2

kaka@mail.ru
password3

lala@mail.ru:password1
coco@mail.ru:password2
kaka@mail.ru:password3