output_description: Print the maximum possible value of floor(Ax/B) - A × floor(x/B) for a non-
  negative integer x not greater than N, as an integer.
  
  * * *
input_description: Input is given from Standard Input in the following format:
  
      
      
      A B N
attempt: a, b, n = map(int, input().split())
  
  
  ans = (a * n) // b - a * (n // b)
  if n >= 1:
      ans2 = (a * (n - 1)) // b - a * ((n - 1) // b)
  else:
      ans2 = 0
  if n >= 2:
      ans3 = (a * (n - 2)) // b - a * ((n - 2) // b)
  else:
      ans3 = 0
  if n >= 3:
      ans4 = (a * (n - 3)) // b - a * ((n - 3) // b)
  else:
      ans4 = 0
  
  if b <= n:
      ans5 = (a * (b - 1)) // b - a * ((b - 1) // b)
  else:
      ans5 = 0
  print(max(ans, ans2, ans3, ans4, ans5))
  
problem_description: Statement
  
  Given are integers A, B, and N.
  
  Find the maximum possible value of floor(Ax/B) - A × floor(x/B) for a non-
  negative integer x not greater than N.
  
  Here floor(t) denotes the greatest integer not greater than the real number t.
samples: [{"input": "5 7 4", "output": "2\n    \n\nWhen x=3, floor(Ax/B)-A\u00d7floor(x/B) = floor(15/7) - 5\u00d7floor(3/7) = 2. This is\nthe maximum value possible.\n\n* * *"}, {"input": "11 10 9", "output": "9"}]