Back Before the College Entrance Exam, I Became a Sensation in the Science Community

The blazing summer sun hung high in the sky, bathing the afternoon in a restless heat that seemed to press against every surface. Even the cicadas had lost the strength to sing. Wu Tong sat at her desk, the air conditioning set to twenty-five degrees, cold air circulating throughout the room, yet she still felt unbearably agitated.

Given the universal set U equals R, set M equals the collection of integers x such that negative one is less than or equal to x minus one is less than or equal to two, and N equals the collection of x such that x equals twice k, where k is an integer, the relationship Venn diagram is as shown. How many elements are there in the shaded region of the diagram?

How many are there?

Wu Tong truly had no idea. At twenty-eight, a working adult who had left the classroom a decade ago, how could she possibly remember high school mathematics problems? Frowning, she rubbed her brow in frustration; who could have anticipated that she would awaken from unconsciousness to find herself back in the summer break of her first year of high school, transformed into a willful, ignorant, and unmotivated academic underachiever?

Her head throbbed painfully, scenes of her father's fatal car accident and her mother hovering between life and death in the emergency room flashed across her mind. Her heart seemed seized by an invisible hand—an agonizing pain that made it difficult to breathe.

Suddenly, the pen in her hand snapped against the desk. Wu Tong looked at the test paper before her.

Everything could still be changed.

I