what is the grading system for levels here on sololearn

Answer 1

https://code.sololearn.com/Wm08eYGJw1hc/?ref=app
https://code.sololearn.com/cClaEQCgEFOf/?ref=app

Answer 2

https://code.sololearn.com/W2zq60Tvn0SU/?ref=app
https://code.sololearn.com/WglQGt564kQU/?ref=app