1. Using a Scanner...
    a. read a string from the standard input, and print it on the standard output
    b. read two numbers from stdin, and print their sum
    c. read a line and print how many characters it contains (including whitespaces)
    d. read a line and print how many words it contains
        - note: the words may be separated by more than one space
    e. read a number (n) and print...
        A. the nth Fibonacci number
        B. the nth row of Pascal's triangle on one line

2.  Using a PrintWriter...
    a. copy the contents of a file into another file line by line
    b. like a., but the lines should be in reverse order (hint: use a Stack)

3.  A file contains filenames. These files contain integer numbers.
    a. Print the name of the file that contains the smallest number.
    b. Print the name of only those files that do not contain duplicate numbers.
       (hint: use a Set)
    c. Calculate the sum of numbers for all of the files.
       Print the filenames with their sums in increasing order.
       (hint: use a Map)

4. For more practice,
   modify all exercises of Ex. 1. so that the results are printed to a file.