(Counting Letters) Modify the program of Fig. to count the number of occurrences of each l...

(Counting Letters) Modify the program of Fig. to count the number of occurrences of each letter rather than of each word. For example, the string "HELLO THERE" contains two Hs, three Es, two Ls, one O, one T and one R. Display the results.

Fig. | Program counts the number of occurrences of each word in a String.