I'm using Chrome. I have never seen the Debug button but only the Run button on the top line in my online IDE. How to make the Debug button out?

Every time I press the Run button, the program never stops at the breakpoints, the bottom terminal always displays the same words whatever I do, and the right panel never works. What should I do?

Thank you!

[![GNU debug not working][1]][1]


  [1]: https://i.sstatic.net/kViCg.png