How do I create this program, I tried to make it work several times but it just won't 
It has to:
first, read in sequence file
second, count Serine residues (S)
third, determine sequence position of all serines
then, print position to screen
finally, print total count to screen

It has to:
first, read in sequence file
second, count Serine residues (S)
third, determine sequence position of all serines
then, print position to screen
finally, print total count to screen