PP2. Week 4: March 29 - April 4
First and last appearance
Given a string of letters. If the letter f appears only once, print its index (indexes are numbered starting from 0).
If the letter f appears two or more times, print the index of the first and of the last appearance.
If letter f is not found in the given string, print nothing.
One string of no more than 255 letters.
Print the answer depending on how many times the letter f appears in the given string.