| Problem Name | Online Judge | Contest | Difficulty Level | |
|---|---|---|---|---|
| 1 | LUCIFER Number | SPOJ | 2 | |
| 2 | G-One Numbers | SPOJ | 2 | |
| 3 | Ra-One Numbers | SPOJ | 2 | |
| 4 | Magic Numbers | Codeforces | Educational Codeforces Round 8 | 6 |
| 5 | Salazar Slytherin's Locket | Codeforces | Manthan, Codefest 17 | 7 |
| 6 | Igor and Interesting Numbers | Codeforces | Codeforces Round #387 (Div. 2) | 9 |