Edit (Jan 22, 2:45 AM UTC): Added Div1E and the editorial is now complete. I am sorry for the delay.
Edit (Jan 21, 9:45 AM UTC): Added the explanation for Div1C/2E, and the problem setters' codes. Div1E will need several more hours. Thank you again for your patience.
First, here are some statistics on this round:
| Division | Registrants | Participants | A Accepted | B Accepted | C Accepted | D Accepted | E Accepted |
| 1 | 1364 | 572 (*) | 294 | 199 | 8 | 113 | 1 |
| (Estimated number of AC by me) | 800 (wrong) | 500 (wrong) | 70 (FAIL) | 90 (ok) | 5 (wrong) | ||
| 2 | 4016 | 2028 | 1355 | 945 | 41 | 5 | 0 |
We are sorry for terribly underestimating the difficulty of the problems (except Div1D), especially Div1A/2C and Div1C/2E.
