Greetings to the CodeForces Community!

The February Long Challenge is just around the corner and I would like you to be a part of it. With 10 programming questions spread across 10 days, you can participate and solve all of Chef's puzzles. Joining me on the problem setting panel, we have:

• Problem Authors: I_love_simplespy (Zhuolin Yang),markysha (Mark Korn), kamranm (Kamran Maharov), chemthan (Trung Nguyen),nerdyninja (Omkar Prabhu),payback_1996 (Ankit Raj),shivam010(Shivam Rathore)
• Problem Tester: Ioser (Hanlin Ren)
• Russian Translator: CherryTree (Sergey Kulik)
• Mandarin Translator: huzecong (Hu Zecong)
• Vietnamese Translator: Team VNOI
• Editorialist: Ioser (Hanlin Ren)
• Statement verifier: Xellos (Jacub Safin)
• Admin: kingofnumbers (Hasan Jaddouh)

I hope you will enjoy solving the problems. Please give your feedback on the problem set in the comments below after the contest.

Contest Details:

Time: 2nd February 2018 (1500 hrs) to 12th February 2018 (1500 hrs). (Indian Standard Time — +5:30 GMT) — Check your timezone.

Details: https://www.codechef.com/FEB18

Registration: You just need to have a CodeChef handle to participate. For all those, who are interested and do not have a CodeChef handle, are requested to register in order to participate.

Hello CodeForces Community!

Chef is ready with 4 exotic dishes which will be served in September Lunchtime. We would like you to take part in Lunchtime and showcase your coding skills by eating all of the dishes. So pull up your socks and get ready for September LunchTime (https://www.codechef.com/LTIME52). Joining me on the problem setting panel, we have:

• Contest Admin: kingofnumbers (Hasan Jaddouh)
• Problem Setter: Ioser (Hanlin Ren)
• Problem Tester & Editorialist: Xellos (Jakub Safin)
• Language Verifier: (Priyank Jaini)
• Russian Translator: CherryTree (Sergey Kulik)
• Mandarin Translator: huzecong (Hu Zecong)
• Vietnamese Translator: Team VNOI

I hope you will enjoy solving them. Please give your feedback on the problem set in the comments below after the contest.

So, note down the details and be there when the contest starts:

Time: 30th September 2017 (1930 hrs) to (2230 hrs). (Indian Standard Time — +5:30 GMT) — Check your timezone.

Details: https://www.codechef.com/LTIME52

Registration: You just need to have a CodeChef handle to participate. For all those, who are interested and do not have a CodeChef handle, are requested to register in order to participate.

Prizes:

• Top 10 performers in Global and Indian category will get CodeChef laddus, with which the winners can claim cool CodeChef goodies. Know more here: https://www.codechef.com/laddu. (For those who have not yet got their previous winning, please send an email to winners@codechef.com)

Good Luck! Hope to see you participating!!

problem 319E(319E - Ping-Pong). Try this data, which makes many accepted program fail:

9
1 -15 -10
1 -11 -5
1 -15 -5
2 3 1
2 1 3
2 2 1
2 1 2
2 2 3
2 3 2