# coding: utf-8



import fractions



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

p = fractions.Fraction(2 * (n-d), n**2) if d != 0 else fractions.Fraction(1, n)

print((float(p * (m-1))))

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

print(((2*(n-d)/n**2 if d!=0 else 1/n)*(m-1)))
# coding: utf-8
import fractions

n, m, d = list(map(int, input().split()))
p = fractions.Fraction(2 * (n - d), n**2) if d != 0 else fractions.Fraction(1, n)
print((float(p * (m - 1))))

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

-# coding: utf-8 -import fractions - -p = fractions.Fraction(2 * (n - d), n**2) if d != 0 else fractions.Fraction(1, n) -print((float(p * (m - 1)))) +print(((2 * (n - d) / n**2 if d != 0 else 1 / n) * (m - 1)))