I have a number of questions:
1. Have you tried the usual Calc I method?
2. What is D(s)?
3. What is d(s)?
4. What are any constraints on any of the parameters, especially the domain for x, and the allowed values of m? (We can see at a glance that 1 is not in the domain.)
5. What does it mean to sum over D(s)? Do you mean there's a dummy variable running over the values in D(s)?