output_description: Print an integer representing the minimum total travel expense.
  
  * * *
input_description: Input is given from Standard Input in the following format:
  
      
      
      N A B
attempt: n = input("整数を入力してください：")
  
  while n.isdigit() == False or int(n) < 1 or int(n) > 20:
      print("Error")
      n = input("整数を入力してください：")
  else:
      n = int(n)
  n = int(n)
  
  
  a = input("整数を入力してください：")
  
  while a.isdigit() == False or int(a) < 1 or int(a) > 50:
      print("Error")
      a = input("整数を入力してください：")
  else:
      a = int(a)
  a = int(a)
  
  b = input("整数を入力してください：")
  
  while b.isdigit() == False or int(b) < 1 or int(b) > 50:
      print("Error")
      b = input("整数を入力してください：")
  else:
      b = int(b)
  b = int(b)
  
  train = n * a
  taxi = b
  
  expense = [train, taxi]
  
  print(min(expense))
  
problem_description: Statement
  
  N of us are going on a trip, by train or taxi.
  
  The train will cost each of us A yen (the currency of Japan).
  
  The taxi will cost us a total of B yen.
  
  How much is our minimum total travel expense?
samples: [{"input": "4 2 9", "output": "8\n    \n\nThe train will cost us 4 \\times 2 = 8 yen, and the taxi will cost us 9 yen, so\nthe minimum total travel expense is 8 yen.\n\n* * *"}, {"input": "4 2 7", "output": "7\n    \n\n* * *"}, {"input": "4 2 8", "output": "8"}]