The lens power for short sight and long sight

A short-sighted eye with far point $F$ needs a concave lens of power $P = -\dfrac{100}{F}$ (with $F$ in centimetres). A long-sighted eye with near point $N$ needs $P = 100 \times \left(\dfrac{1}{25} - \dfrac{1}{N}\right)$ to read at $25\ \text{cm}$. You will make the program find both sets of powers, and pick out the strongest lens for short sight.

Your tasks.

1. Inside the first loop, work out P for the far point F.
2. Inside the second loop, work out P for the near point N.
3. Find strongest, the most negative power in the list for short sight.