Write a Python program to sum the missing numbers in a given list of integers.

Example: if the list is [0, 2, 4, 7], then the sum is 15 (1+3+5+6).

Write a Python program to print the even numbers from a given list.

Write a Python program to count the number 3 in a given list.

Write a Python program to find the least common multiple (LCM) of two positive integers.