7115번 - Circle 출처다국어분류

An endless checked page consists of square cells. The length of each side of the cell is k units. Smuidris drew a circle of radius r units on this page. The center of the circle was located on the intersection of two lines (in the middle of 4 cells). Then Smuidris painted all the cells that were crossed by the circle (that contained a part of the circle). (If the circle only touched a corner of the cell, Smuidris did not paint the cell).

You are to write a program that for given values of natural numbers k and r (k < 30000, r < 30000) computes un outputs the number of cells painted by Smuidris.