Feynman

Richard Phillips Feynman was an American physicist and Nobel laureate. He studied theoretical physics and pioneered the field of quantum computing. His books, such as Surely You're Joking, Mr. Feynman! and What Do You Care What Other People Think?, were beloved by many readers and have also been translated and published in Korea. For a long time he was captivated by making and solving puzzles, locks, and ciphers.

One day, a note believed to belong to Feynman was found on a farm in South America. It contained writings about mesons and electromagnetism, and its very last line held the following quiz:

"How many distinct squares are there inside an $N \times N$ square grid?"

Write a program that answers this quiz. For example, when $N = 2$ the answer is $5$.

The input consists of several test cases. Each test case is a single line containing the number of squares $N$ along one side of the grid. ($1 \le N \le 100$)

The last line of the input contains a single $0$, which is not processed.

For each test case, print the number of distinct squares, one per line.