Questions about C syntax used in C++

First some background: I recently started programming in C++.As we all know that C is not required for C++, so I picked c++ and started learning from books without any knowledge of C!

Now, I passed the introductory phase and learnt enough to practise some basic questions for self assessment. I found a site called HackerRank(One of the top site to practise coding).So I selected C++ on that site and opened the first question! I cleared the first 5-6 basic questions! But then there was a code with printf(),scanf() and other.. So I googled it and found out that's C syntax! Not only on HackerRank, But I encountered C syntax in many stacks overflow Q&As. It's quite difficult to understand!

So, My questions are: what should I do? Should I learn this syntax? And if Yes than how much should I learn? Or Is there any other way?