In Chinese, what is the most difficult character to write or read?

In Chinese, the most difficult character is biang.

I. There is a unique noodle dish in Guanzhong, Shaanxi Province called "biang-biang noodles", which is between "dry noodles" and "soup noodles".

The Biang character is said to have the most strokes of any Chinese character in the world. The character's font is not included in any traditional dictionaries, including the Kangxi Dictionary, and its pronunciation is impossible to spell in Mandarin.

Three, it is written in this poem: a little fly up to the sky, the Yellow River curved at both ends, eight big open mouth, the word into the left a button, right a button, left a long, right a long, the middle of a horse king, the bottom of the heart word, the word beside the moon, two thieves child standing next to the seat on the car to go in all directions.