output_description: Print the cost of the Ferris wheel for Takahashi.
  
  * * *
input_description: Input is given from Standard Input in the following format:
  
      
      
      A B
attempt: def main():
      mod = 10**9 + 7
      n, m, k = list(map(int, input().split()))
      # 　ある配置を固定した時、その2つの配置でmanhattan距離が計算される回数は、他の組み合わせ数。
      combination = mod_combination(n * m - 2, k - 2)
      x = y = 0
      for i in range(1, n):
          x += i * (n - i)
      for j in range(1, m):
          y += j * (m - j)
  
      return (((m**2) % mod * x % mod) + ((n**2) % mod * y % mod)) * combination % mod
  
  
  def mod_combination(n, r, mod=10**9 + 7):
      fact = 1
      for i in range(n - r + 1, n + 1):
          fact = fact * i % mod
      divisor = 1
      for j in range(1, r + 1):
          divisor = divisor * j % mod
      return int(fact / divisor)
  
  
  main()
  
problem_description: Statement
  
  Takahashi, who is A years old, is riding a Ferris wheel.
  
  It costs B yen (B is an even number) to ride the Ferris wheel if you are 13
  years old or older, but children between 6 and 12 years old (inclusive) can
  ride it for half the cost, and children who are 5 years old or younger are
  free of charge. (Yen is the currency of Japan.)
  
  Find the cost of the Ferris wheel for Takahashi.
samples: [{"input": "30 100", "output": "100\n    \n\nTakahashi is 30 years old now, and the cost of the Ferris wheel is 100 yen.\n\n* * *"}, {"input": "12 100", "output": "50\n    \n\nTakahashi is 12 years old, and the cost of the Ferris wheel is the half of 100\nyen, that is, 50 yen.\n\n* * *"}, {"input": "0 100", "output": "0\n    \n\nTakahashi is 0 years old, and he can ride the Ferris wheel for free."}]