Drawings on a piece of paper in the box

Vasya is a leaf in a section consisting of N cells in the horizontal and vertical M cells, and cell line on the edge of the leaflet are also visible. How many different rectangles can on this piece of paper to draw Vasya, if he only knows how to draw the lines?

Input

In a single line through the space are two numbers M and N. All input data are natural numbers not exceeding 10^10000.

Output

Single number - the desired number of rectangles.

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