你好，Codeforces!

We (WDOI team) are delighted to invite you to participate in Codeforces Round 1098 (Div. 2), which will be held on May/16/2026 17:35 (Moscow time). You will be given $$$6$$$ problems, including two problems each having easy and hard versions, and $$$2$$$ hours and $$$15$$$ minutes to solve them. This round will be rated for the participants with rating lower than 2100.

The problems are authored and prepared by Sugar_fan and me.

The scoring distribution: to be released soon ...

We would like to express our sincere thanks to the following individuals for their contributions and for making this round possible:

• Sugar_fan for his incredibly dedicated coordination and support,and he has also deleted some problems and modified some to make the round better.

• Um_nik for preliminary review of the round and giving me courage.

• Alexdat2000 for Russian translations.

• Otomachi_Una, juan_123, CirnoNine, fanhuaxingyu for their valuable contribution to the problems.

• EnofTaiPeople, Welcome24ever, Mitsukasa_Ayase, SATSKY_2025target_LGM, Serval, __baozii__, juan_123, Zheng_iii, Arpa, CirnoNine, Anoth3r, hushuqi_qwq, fanhuaxingyu, SunJude, ddndd, RioBlus, bluket, bzy, CSP_Sept, YoungLau, ihy, 2021cjx, alij_8, gouhhmumu for testing the round.

• MikeMirzayanov and KAN for the amazing platforms.

• And finally, You for participating.

We are a team made up of fans of both competitive programming and the Touhou Project. Although this isn’t our first time hosting contests on Codeforces — we previously organized Codeforces Round 796 (Div. 1) and Codeforces Round 796 (Div. 2) — I authored most of the problems in this round with little assistance. In 2022, most of our members were Olympiad in Informatics (OI) participants, but over the four years since then, many have stepped away from OI and competitive programming. While the older generation may eventually fade away, newcomers like me aim to keep our community alive by injecting fresh energy and passion into what we love. I hope this kind of pure love persists and carries on.

Across these six problems, you will meet characters with their own distinct personalities and beliefs.

Marisa stole Reimu’s takeout and vanished before the shrine maiden could react. Hungry and sharp-eyed, Reimu marched to the Scarlet Devil Mansion, challenged Remilia to a fierce game of Hisoutensoku, and claimed victory—along with her lunch. Near the Misty Lake, Cirno found a cold number frozen in the ice. With a child’s certainty, she reshaped it into a beautiful ice crystal, perfect and gleaming. Atop the Youkai Mountain, Sanae watched the stars and prayed for fortune, her quiet hopes rising with each passing light. Elsewhere, an Amanojaku teetered on the edge of ruin. In Yukari’s contest, it solved a problem others deemed impossible, reversing its fate and reclaiming its place.

Hearing of these scattered lives, Momoyo built a grand network across Gensokyo — linking shrines, mansions, and factions. Conflict gave way to conversation, and peace settled softly over the land. Harmony replaced trouble, and laughter returned to the air.

Help them overcome these trials through your logic, and find satisfaction in lending a hand. We hope you enjoy the round. Good Luck and Have Fun!

May Gensokyo’s peace endure — and may the real world, too, know such days.