To assist self-studies of C programming at home by novice students, we have studied the grammar-concept under-standing problem (GUP), the value trace problem (VTP), and the phase fill-in-blank problem (PFP) as introductory programming exercise problems. A GUP instance asks the keyword in a given source code that corresponds to the grammar concept described in the question. A VTP instance asks the value of an important variable or message in the code. A PFP instance asks a set of elements or a message to be filled in for each blank in the code. In any instance, the correctness of an answer is marked through string matching with the correct one. In this paper, we present a study of three introductory problems to novice students. We generated GUP/VTP/PFP instances by following the C programming course curriculum in Nihon University, Japan, and assigned them to its first-year undergraduate students who solved them at home for the course review before the final examination. The solution results reveal difficulty differences among the three introductory problems and three student groups in terms of solution performances.