ok guys... so here's a nice one...

suppose i have a matematical expression with variables less than 10 and greater than 0... and i divide the mathematical expression in leaves and nodes, being the operands the leaves and the operators the nodes...

something like this:

```
(w+x)*(y-z)
[B]*[/B]
/ \
[B]+[/B] [B] -[/B]
/ \ | \
[B]w x y z[/B]
```

hope you understand it... :P

the problem is: the mathematical expression must be input by the user, and the program must break it down... and at the end it must show the result...