gistfile1.py

#!/usr/bin/python
#
# author: [email protected]
# usage: cat file.input | ./qround-problem-a.py > file.output
 
import sys
 
# 計算建完 n 個農場所需時間
def calc_time(c, f, n):
    tt = 0.0
    for i in range(n):
        tt += (c / (2 + i * f))
    return tt

def solve():
    s = sys.stdin.readline()[:-1]
    c, f, x = [float(x) for x in s.split()]
    n = (int)(((x * f - c - c) / (c * f) ) - 1) + 1  # 最佳解時的農場數量

    postfix = " >>" + repr(n)
    if n <= 1:
        t = (x / 2)
    else:
        t = calc_time(c, f, n) + (x / (2 + n * f))

    return repr(round(t, 7))
 
t = (int)(sys.stdin.readline())
for i in range(t):
    print 'Case #' + repr(i+1) + ': ' + solve()