awk again

I have a list of records like below:

N_p_hello[f]_lolo where p and f is a number from 0 to 1000 and i would like to substitute the hello[f] with the number f so it will be
N_p_f_lolo

I tried some staff but i cant find a way

my question could be is there any way of saying any character in awk like the "*" operator
As far as i understand there is the "." operator which means any but only one character.
for example A.U means any string that has three characters and begins with A and ends with U.

But if we dont know how many characters we have within?

I don't use awk, I use python, so there will be differences.

\d pulls out a single digit (0-9) and you can follow it with {x,y} where x is the least amount of digits and y is the max

Syntax might be different for you though

Why don't you post what you'ave tried.