# Day4: Secure Container

## Problem

You arrive at the Venus fuel depot only to discover it's protected by a
password. The Elves had written the password on a sticky note, but someone
threw it out.

However, they do remember a few key facts about the password:

* It is a six-digit number.
* The value is within the range given in your puzzle input.
* Two adjacent digits are the same (like 22 in 122345).
* Going from left to right, the digits never decrease; they only ever increase
or stay the same (like 111123 or 135679).

Other than the range rule, the following are true:

* 111111 meets these criteria (double 11, never decreases).
* 223450 does not meet these criteria (decreasing pair of digits 50).
* 123789 does not meet these criteria (no double).

How many different passwords within the range given in your puzzle input meet
these criteria?