Is it true,that input\output for ALL problems is keyboard

> Is it true,that input\output for ALL problems is keyboard

No, that's not true. It's stdin\stdout. Normally, this
is keyboard\monitor, but you can use other things,
for example files:

programname <inputfile >outputfile
(Works in unix. In win, I don't know.)

That uses the inputfile for input and the outputfile for
output.

Stefan Pochmann