new_contents: class Solution:
      # @param m, an integer
      # @param n, an integer
      # @return an integer
  
      def rangeBitwiseAnd(self, m, n):
          cnt = 0
          while m != n:
              m >>= 1
              n >>= 1
              cnt += 1
          return m << cnt
  
subject: add solution for Bitwise AND of Numbers Range