output_description: Print the sum of the ABC numbers of all the 3^Q strings, modulo 10^9 + 7.
  
  * * *
input_description: Input is given from Standard Input in the following format:
  
      
      
      S
attempt: class ABC104:
      modulus = 10**9 + 7
  
      def __init__(self, s):
          self.s = s
          self.n = len(s)
  
      def dp(self, i, j):
          """
          dynamic programming for abc 104
          :param i: index of the given string
          :param j: count of letters of composed string (like 'ABC')
          :return: the number of cases
          """
          if i == self.n:
              if j == 3:
                  return 1
              else:
                  return 0
  
          if i < self.n and j == 3:
              m = 3 if self.s[i] == "?" else 1
              return m * self.dp(i + 1, 3) % self.modulus
  
          if i < self.n and j < 3:
              m1 = 3 if self.s[i] == "?" else 1
              m2 = 1 if self.s[i] == "?" or self.s[i] == "ABC"[j] else 0
  
              _pass = m1 * self.dp(i + 1, j) % self.modulus
              _take = m2 * self.dp(i + 1, j + 1) % self.modulus
  
              return _pass + _take
  
  
  if __name__ == "__main__":
      abc = ABC104(input())
      print(abc.dp(0, 0))
  
problem_description: Statement
  
  The _ABC number_ of a string T is the number of triples of integers (i, j, k)
  that satisfy all of the following conditions:
  
    * 1 ≤ i < j < k ≤ |T| (|T| is the length of T.)
    * T_i = `A` (T_i is the i-th character of T from the beginning.)
    * T_j = `B`
    * T_k = `C`
  
  For example, when T = `ABCBC`, there are three triples of integers (i, j, k)
  that satisfy the conditions: (1, 2, 3), (1, 2, 5), (1, 4, 5). Thus, the ABC
  number of T is 3.
  
  You are given a string S. Each character of S is `A`, `B`, `C` or `?`.
  
  Let Q be the number of occurrences of `?` in S. We can make 3^Q strings by
  replacing each occurrence of `?` in S with `A`, `B` or `C`. Find the sum of
  the ABC numbers of all these strings.
  
  This sum can be extremely large, so print the sum modulo 10^9 + 7.
samples: [{"input": "A??C", "output": "8\n    \n\nIn this case, Q = 2, and we can make 3^Q = 9 strings by by replacing each\noccurrence of `?` with `A`, `B` or `C`. The ABC number of each of these\nstrings is as follows:\n\n  * `AAAC`: 0\n  * `AABC`: 2\n  * `AACC`: 0\n  * `ABAC`: 1\n  * `ABBC`: 2\n  * `ABCC`: 2\n  * `ACAC`: 0\n  * `ACBC`: 1\n  * `ACCC`: 0\n\nThe sum of these is 0 + 2 + 0 + 1 + 2 + 2 + 0 + 1 + 0 = 8, so we print 8\nmodulo 10^9 + 7, that is, 8.\n\n* * *"}, {"input": "ABCBC", "output": "3\n    \n\nWhen Q = 0, we print the ABC number of S itself, modulo 10^9 + 7. This string\nis the same as the one given as an example in the problem statement, and its\nABC number is 3.\n\n* * *"}, {"input": "????C?????B??????A???????", "output": "979596887\n    \n\nIn this case, the sum of the ABC numbers of all the 3^Q strings is\n2291979612924, and we should print this number modulo 10^9 + 7, that is,\n979596887."}]