text: # ========================
  #       Information
  # ========================
  
  # Direct Link: https://www.hackerrank.com/challenges/s10-geometric-distribution-1/problem
  # Difficulty: Easy
  # Max Score: 30
  # Language: Python
  
  # ========================
  #         Solution
  # ========================
  
  A, B = map(int, input().strip().split(' '))
  C = int(input())
  
  P = float(A/B)
  
  RES = (1-P) ** (C-1) * P
  
  print(round(RES, 3))
  