input — prompt for user input
x = input(message [, "string"])
character string
the character string "string" (may be
	    abbreviated to "s")
real number (or character string if
	    "string" is in the calling sequence)
input(message) gives the user the prompt in the text string and 
    then waits for input from the keyboard. 
    The input can be expression which is evaluated by evstr.
    If nothing but a carriage return is
    entered at the prompt input(message) returns an empty matrix
    
    Invoked with two arguments, the output is a character string which is the
    expression entered at keyboard.  If nothing but a carriage return is
    entered at the prompt input(message) returns  a single white
      space  " ".