The prompt to "Enter integer values:" is nice when you run the program and type the values yourself, but it is not needed when you provide the input through a pipe or input redirection. Since you know how to tell if the scanf succeeded, you might try doing the scanf first, then printing the prompt if it fails. However, that does not work. Why? Use vi to make a file with your answer, then use cat to display it on the log$.($That is$,$ you don't have to do it$,$ just provide an explanation for why it would not work.$)$