Exercise $8\mathrm{.}1-$ Counting characters, words and lines in a file

Write a program that counts the number of characters,words and lines in a file. words are seperated by space, lines are separated by $"n".$

Program should prompt the user for the input file.

Sample input file : customers.txt

Sample output:

Enter a filename: customers.txt

$63$ characters

$8$ words

$4$ lines