A shuttle bus takes minutes to drive from one stop to the next, and waits minutes at each stop to let passengers board. Leo takes minutes to walk from one bus stop to the next. As Leo reaches a bus stop, if the bus is at the previous stop or has already left the previous stop, then he will wait for the bus. Otherwise he will start walking toward the next stop. Suppose the bus and Leo start at the same time toward the university, with the bus stops behind. After how many minutes will Leo board the bus?
30
31
32
33
34
