I'm trying to write a program in C that takes 10 command line arguments and performs certain actions on them. I already have the part that accepts the 10 arguments `int main(int argc, char **argv)` and the part that outputs the result once all 10 are entered by the user `printf(" %s", argv[i]);`. 

I'm just trying to figure out how to perform the actions themselves on each command line argument entered, namely:

* remove all special symbols such as `(*&%^’$+_`.
* remove all non-letters

and finally:

* If the argument contains one or more digits, assuming that the first
digit seen is n, replace that arg by the nth arg (the only exception is 0, which should map to the 10th argument). So for example, if the argument entered is `764`, this argument gets replaced by the 7th arg.

**Edit:** Updated with better example below

Here is an example input (10 user-inputed arguments):

```
sda 789 io90 poi 4kl24PP +df_1JK MN BV XC __5555

```

and what the output should be:

```
sda  MN  XC  poi  poi  sda  MN  BV  XC  klPP

```

(also notice how 789 maps to the 7th output, which is MN)