(https://atcoder.jp/contests/abc290/tasks/abc290_e)
( https://atcoder.jp/contests/abc290/editorial/5809 )
Can anyone please prove the given formula that is used to calculate total number of lines ? 
tagging top contributors for better reach awoo, -is-this-fft-, nor, IceKnight1093
| № | Пользователь | Рейтинг |
|---|---|---|
| 1 | tourist | 3845 |
| 2 | jiangly | 3707 |
| 3 | Benq | 3630 |
| 4 | orzdevinwang | 3573 |
| 5 | Geothermal | 3569 |
| 5 | cnnfls_csy | 3569 |
| 7 | jqdai0815 | 3532 |
| 8 | ecnerwala | 3501 |
| 9 | gyh20 | 3447 |
| 10 | Rebelz | 3409 |
| Страны | Города | Организации | Всё → |
| № | Пользователь | Вклад |
|---|---|---|
| 1 | maomao90 | 171 |
| 2 | adamant | 163 |
| 3 | awoo | 162 |
| 4 | nor | 153 |
| 5 | maroonrk | 152 |
| 6 | -is-this-fft- | 151 |
| 7 | TheScrasse | 150 |
| 8 | atcoder_official | 145 |
| 8 | Petr | 145 |
| 10 | pajenegod | 144 |
My reply is a bit off-topic, but I find the user editorial a bit easier to understand. You can google translate it, but just by looking at the Python code, it is easier to understand than the official editorial.