### The task

Small-headed is a sequence of numbers if its first element is smaller then the last,
the second element is smaller than the second last, and so on...
To be more precise:
The *a*_{1}, *a*_{2}, ...,
*a*_{n} sequence is small-headed, if *a*_{1} > 0, and
for all *i*, 1 ≤ *i* ≤ *n*```
div
```

2 (where `div`

is integer division),
*a*_{i} <
*a*_{n+1-i}.
Examples: 1 2; 4 2 5 3 5; 1 2 3 4 3 2. Counter-examples: 1 1;
4 2 5 3 4; 1 2 3 3 1 0.
Write a function called `smallheaded`

which satisfies the following:

You are allowed to define auxiliary functions.
### Examples:

smallheaded 4 = 5 (* because 4_{5} = 4 is smallheaded, but 4_{4} = 1 0, 4_{3} = 1 1, 4_{2} = 1 0 0 are not *)
smallheaded 11 = 3 (* because 11_{3} = 1 0 2 is smallheaded, but 11_{2} = 1 0 1 1 are not *)
smallheaded 145 = 7 (* because 145_{7} = 2 6 5 is smallheaded, but... *)
smallheaded 293 = 3 (* because 293_{3} = 1 0 1 2 1 2 is smallheaded, but ... *)

In the examples, *d*_{r} denote the decimal number *d*
written in *r*-base.