一只大象口渴了，要喝20升水才能解渴，但现在只有一个深h厘米，底面半径为r厘米的小圆桶(h和r都是整数)。

问大象至少要喝多少桶水才会解渴。(设PAI=3.14159)(输入输出样例中的?代表一个空格)

输入一行：小圆桶的深h，和底面半径r，单位都是厘米。

输出两行：第一行提示输入语句；第二行为大象至少要喝水的桶数。-An elephant thirsty, drink 20 liters of water to quench their thirst, but now only a centimeter deep h, a bottom radius r cm small drums (h and r are integers). Q. How many buckets of water elephants drink at least until thirst. (Based PAI = 3.14159) (? Input sample output representative of a space) input line: small drums deep h, and a bottom radius r, units are centimeters. The output of two lines: the first line prompt for the statement　barrels for at least a second elephant drinking behavior.