An architect wants to construct a vaulted building supported by a family of arches Cn.
fn(x) = -nx - xlog(x) is the equation of the arch Cn where `x` is a positive real number (0 < x <= 1), `log(x)` is the natural logarithm (base e), `n` a non negative integer. Let fn(0) = 0.
Be An the point of Cn where the tangent to Cn is horizontal and Bn+1 the orthogonal projection of An on the x-axis (it means that An and Bn+1 have the same x -coordinate). 
Kn is the intersection of Cn with the x-axis. 
The figure shows C0, A0, B1, K0 as C(0), A0, B1, K0. 
![alternative text](https://i.imgur.com/Td9aWIJ.png)
The architect wants to support each arch Cn with a wall of glass filling the **curved** surface An Bn+1 Kn under the curve Cn.
On the drawing you can see the surface `A0 B1 K0` in blue.
He asks if we could calculate the weight of the surface of glass he needs to support all arches C0...Cn where n is a positive integer knowing he can choose glass thickness hence glass weight per square unit of surface.
He gives us the absolute value of A0 B1 K0 area (in blue); call it `i0` which is approximately `0.14849853757254047` in square units.
## Task
Write the function `weight` with parameters `n` and `w` where `n` is the number of arches to consider (n >= 1) and `w` is the weight of a square unit of glass depending on the wall thickness. 
This function should return the weight of n glass walls as described above.
## Example
```
weight(10, 700) -> 120.21882500408238
weight(8, 1108) -> 190.28922301858418
```
## Hint:
There is no integral to calculate. You can plot C1 and try to see the relationship between the different Cn and then use `i0`.
## Note: 
- don't round or truncate your result
from math import e
def weight(n, w):
    return -0.17174117862516716*(e**(-2*n) - 1)*w
from math import e
def weight(n, w):
    return -0.17174117862516716*(e**(-2*n) - 1)*w