Introduction - If you have any usage issues, please Google them yourself
POJ A+B
Q: Where are the input and the output?
A: Your program shall always read input stdin (Standard Input) and write output to stdout (Standard Output). For example, you can use scanf in C or cin in C++ to read stdin, and use printf in C or cout in C++ to write to stdout.
You shall not output any extra data to standard output other than that required by the problem, otherwise you will get a Wrong Answer .
User programs are not allowed to open and read from/write to files. You will get a Runtime Error or a Wrong Answer if you try to do so.