The painted over sections 2

On a leaflet in a section with a cell in M millimeters have drawn a circle in radius of R millimeters and have painted over all the cells crossed with a circle. All other cells including what circles only concern, have left not painted over. The center of a circle is always placed on crossing of cells. To define, how many cells N have been painted over.

Input

In a unique line through a blank of 2 numbers: M and R (M, R <= 40000). Output

Required number of painted over cells N

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Examples