hrw最近看到一个有趣的几何题，题目描述是这样的：一个大圆盘里面放入许多小圆盘，每个小圆盘必须接触大圆盘边缘且与其他小圆盘不能相交，但它们可以互相接触，每个小圆盘具有相同的半径，求此条件下能否放入n个小圆盘。
签到题
Input
Multiple sets of test data，The first line contains three integers n, R and r (1 ≤ n ≤ 100, 1 ≤ r, R ≤ 1000) — the number of plates, the radius of the table and the plates' radius.and you can think the pi is 3.1415927
Output
Print "YES" (without the quotes) if it is possible to place n plates on the table by the rules given above. If it is impossible, print "NO".Remember, that each plate must touch the edge of the table.
Sample Input
4 10 4
2 10 10
Sample Output
YES
NO