I want to know the answer to the following question:
How many public schools are regulated by the 1868 Public Schools Act?
All the background I'm provided with is that "Following the public school tradition, Eton is a full boarding school, which means all pupils live at the school, and it is one of four such remaining single-sex boys' public schools in the United Kingdom (the others being Harrow, Radley, and Winchester) to continue this practice.". Is that enough to answer the question?