Back in the day, when phones were "landlines", computers were the size of minivans, and Brian Kelly was a linebacker at Assumption College, the pride and joy of every engineering geek was his HP scientific calculator. Even the mighty Woz 1 cherished his legendary HP-35.

Of course, since the old timers back then were super awesome (unlike today's young whippersnappers), they didn't use the standard lame infix notation to perform their calculations; instead, they used the uber 1337 reverse polish notation.

That is, rather than entering in `<operand> <operation> <operand>`, you would enter in `<operand> <operand> <operation>` to perform a calculation on the RPN calculator. Using RPN eliminates the need for paretheses and orders of operation since it is never ambiguous what operands are used with which operation; the operation is always applied to the previous arguments.

This means that if you wanted to perform `3 + 4`, you would have to enter in:

```3 4 +
```

To prove that you too are uber awesome and to relive some of the glory days, you are to create a RPN calulator that can perform: `+`, `-`, `*`, `/`, and `^`. For the sake of nostalgia, you should output the results of the caluation as digital LED numbers as shown here:

```    _  _     _  _  _  _  _  _
| _| _||_||_ |_   ||_||_|| |
||_  _|  | _||_|  ||_| _||_|
```

Each digit is composed of a combination of `|` and `_` and occupies the same amount of space.

For a negative number such as `-3`, you should display:

```    _
_  _|
_|
```

## Input

Each line in the input will be a RPN expression that you have to calculate.

```4
5 8 * 1 +
```

## Output

For each RPN expression, output the calculation as a LED number.

```|_|
|

|_|  |
|  |
```

## Submission

```\$ cd path/to/cse-30872-fa18-assignments     # Go to assignments repository
\$ git checkout master                       # Make sure we are on master
\$ git pull --rebase                         # Pull any changes from GitLab

\$ git checkout -b challenge02               # Create and checkout challenge02 branch

\$ \$EDITOR challenge02/program.cpp           # Edit your code

\$ git commit -m "challenge02: done"         # Commit your changes

\$ git push -u origin challenge02            # Send changes to GitLab
```

To check your code, you can use the `.scripts/submit.py` script or curl:

```\$ .scripts/submit.py
Submitting challenge02 assignment ...
Submitting challenge02 code ...
Result Success
Score 6.00

\$ curl -F source=@challenge02/program.cpp  https://dredd.h4x0r.space/code/cse-30872-fa18/challenge02
{"score": 6, "result": "Success"}
```

Once you have commited your work and pushed it to GitLab, member to create a merge request. Refer to the Reading 01 TA List to determine your corresponding TA for the merge request.

1. Woz spilled my french fries. I will never forget.