n, m, d = list(map(int,input().split()))

if d == 0:

    p = n

elif n < d:

    p = 0

else:

    p = (n * 2 - d * 2)

r = p / (n * n)

a = r * (m - 1)

print((round(a, 8)))

n, m, d = list(map(int,input().split()))

if d == 0:

    p = n

else:

    p = (n * 2 - d * 2)

r = p / (n * n)

a = r * (m - 1)

print((round(a, 8)))

n, m, d = list(map(int, input().split()))
if d == 0:
    p = n
elif n < d:
    p = 0
else:
    p = n * 2 - d * 2
r = p / (n * n)
a = r * (m - 1)
print((round(a, 8)))

n, m, d = list(map(int, input().split()))
if d == 0:
    p = n
else:
    p = n * 2 - d * 2
r = p / (n * n)
a = r * (m - 1)
print((round(a, 8)))

-elif n < d: -    p = 0