It's a Pokemon battle! Your task is to calculate the damage that a particular move would do using the following formula (not the actual one from the game):

damage = 50 * (attack / defense) * effectiveness Where:

attack = your attack power defense = the opponent's defense effectiveness = the effectiveness of the attack based on the matchup (see explanation below) Effectiveness:

Attacks can be super effective, neutral, or not very effective depending on the matchup. For example, water would be super effective against fire, but not very effective against grass.

Super effective: 2x damage Neutral: 1x damage Not very effective: 0.5x damage To prevent this kata from being tedious, you'll only be dealing with four types: fire, water, grass, and electric. Here is the effectiveness of each matchup:

* fire > grass
* fire < water
* fire = electric
* water < grass
* water < electric
* grass = electric

For this kata, any type against itself is not very effective. Also, assume that the relationships between different types are symmetric (if A is super effective against B, then B is not very effective A).

The function you must implement takes in:

1. your type
2. the opponent's type
3. your attack power
4. the opponent's defense