import math

from decimal import Decimal

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

if d == 0:

    t = math.exp(float(Decimal.from_float(math.log(n)+math.log(m-1)-2*math.log(n))))

    print(t)

else:

    t = 2.0 * (n - d)*(m-1) / n ** 2

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

if d == 0:

    print((n * (m - 1) / n ** 2))

else:

    print((2*(n - d) * (m - 1) / n ** 2))
import math
from decimal import Decimal

n, m, d = list(map(int, input().split()))
if d == 0:
    t = math.exp(
        float(Decimal.from_float(math.log(n) + math.log(m - 1) - 2 * math.log(n)))
    )
    print(t)
else:
    t = 2.0 * (n - d) * (m - 1) / n**2
    print(t)

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

-import math -from decimal import Decimal - -    t = math.exp( -        float(Decimal.from_float(math.log(n) + math.log(m - 1) - 2 * math.log(n))) -    ) -    print(t) +    print((n * (m - 1) / n**2)) -    t = 2.0 * (n - d) * (m - 1) / n**2 -    print(t) +    print((2 * (n - d) * (m - 1) / n**2))