Think about the steps you take to solve it yourself. Write the steps down one below the other and write a comment beside each one to say what your did to get from the previous step to the current step. Think about how you could write some code to perform the step, then think about the pattern you recognized in the first step and how you could write code to recognize that pattern.

When you have code that tries to do all that, come back to us for help getting the code to work. We will want to see the code and the test cases you are using.