Define $input :
1 There are several errors in the input.
2 A new or recently revised edition of input data.
3 A character that groups or separates words or values in a line of input.
4 One, or a sequence of, input states.
5 A single input operation on a terminal.
6 The number of circuits that can be fed input signals from an output device.
7 To obtain a record from an input file.
8 A check made on input data to insure that it does not exceed a maximum figure.
9 The output power can never equal the input power, for there are always losses.
10 The minimum input span available is 50C.