Drawings on a piece of paper in the box#1328
You have a piece of squared paper consisting of cells horizontally and cells vertically, with grid lines on the edges also visible. How many different rectangles can you draw on this paper if you can only draw along the lines?
A single line contains two numbers and separated by a space. All input data are natural numbers not exceeding 10^{10000}.
Output a single number — the required number of rectangles.
Example 1