online judge was not cleared to me , what is online judge ,where we can apply online judge . so i want brief description.
Online judge -input & output
online judge is not a c++ concept 
online judge is the judge used in hackerblocks
when you submit your solution on hackerblocks it was judged by online judge
whether your output is correct or not
in this video sir explained how to take multiple inputs and print output which is common in online challenges
i hope this helps
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