Kata

There are pillars near the road. The distance between the pillars is the same and the width of the pillars is the same. Your function accepts three arguments:

1. number of pillars (≥ 1);
2. distance between pillars (10 - 30 meters);
3. width of the pillar (10 - 50 centimeters).

Calculate the distance between the first and the last pillar in centimeters (without the width of the first and last pillar).