Reading in a Circle

A classroom has N children with Roll Nos 1 to N. They are reading a story with P paragraphs. The teacher makes all thee children sit down in a circle ordered by ascending roll no. Every child must read aloud a paragraph of the story in sequence. For example, if the teacher starts with child 5 the order will be 5, 6, 7 .... N-1, N, 1, 2, .... until the P paragraphs are read. The child who reads th