I reviewed all the contests I got negative delta in this year. Then, I found something interesting!

Teza Round 1 (Codeforces Round 1015, Div. 1 + Div. 2) I spent 2 hours in 2084E - Blossom(Given an incomplete permutation and count the possible valid permutations) so that I didn't have enough time to solve G1. Rating -= 59.

Codeforces Round 1021 (Div. 1) No counting problems but I spent more than 1 hour in a stupid ExGCD problem. Rating -= 38.

Codeforces Round 1024 (Div. 1) I didn't solve 2101D - Mani and Segments(Given a permutation and count the valid subarrays, which is only *2500) within 1.5 hours. Rating -= 28.

EPIC Institute of Technology Round Summer 2025 (Codeforces Round 1036, Div. 1 + Div. 2) I didn't solve 2124F2 - Appending Permutations (Hard Version)(Given some restrictions, count the valid permutations) as I quickly solved the easy version with 1.5 hours left. Rating -= 2.

Codeforces Round 1040 (Div. 1) I didn't solve 2129D - Permutation Blackhole(Given some restrictions, count the valid permutations), which is obviously a range DP. Rating -= 96.

Atto Round 1 (Codeforces Round 1041, Div. 1 + Div. 2) I didn't solve 2127F - Hamed and AghaBalaSar(Calculate F(a) for all valid array a modulo 1e9+7). I even couldn't come up with any possible observations except transforming the function F and try to enumerate a[n] and how many times it appears(obviously O(nlnn)). Rating -= 43.

I have a conclusion now.

If one contest have a problem like counting valid permutations or given few numbers and calculate something % 1e9+7 / 998244353 in the place of 1D, I can easily get a negative delta while everyone other than me can solve it with ease.

What should I do???