P7313 [COCI 2018/2019 #3] Magnus

Magnus lost to Kile in chess, so he became obsessed with programming. He decided to go to the COCI contest to try his luck. After hearing that Magnus wanted to participate in COCI, Kile gave him this warm-up problem.

You are given a word of length $N$. Delete any number of letters from the word so that you can form as many `HONI` as possible.

Input a string of length $N$ containing only English letters, representing the given word.

Output the maximum number of `HONI` that can be formed.

#### Explanation of Sample 2 You can delete the earliest $3$ occurrences of each of the four letters `H`, `O`, `N`, `I` from the original word to obtain `HONI`. #### Constraints For $100\%$ of the testdata, $1 \le N \le 10^5$. #### Notes **The score of this problem follows the original COCI setting, with a full score of $50$.** **Translated from [COCI2018-2019](https://hsin.hr/coci/archive/2018_2019/) [CONTEST #3](https://hsin.hr/coci/archive/2018_2019/contest3_tasks.pdf) _T1 Magnus_.** Translated by ChatGPT 5