3.HangOver
http://acm.fzu.edu.cn/problem.php?pid=1002
import sys
from fractions import Fraction
import decimal
decimal.getcontext().prec=2
for c in sys.stdin:
c=float(c)
if c==0.00:
break
i=2
length=0
while True:
length+=Fraction(1,i)
if length>=c:
break
else:
i+=1
print('%d card(s)'%(i-1))