I was trying to solve a question.

recursion(n/10);
cout << n%10 << " ";

How to know for which test case my code fails??

I see the input in the test case is getting trimmed

https://imgur.com/wHpnUyD

1708A — 30

I really would like to know, where my code went wrong.

problem is 1708A — 30

and pretest case is 2.