Program output:

Walking over: 0: Everything
Walking over: 1: Arts and Humanities
Walking over: 1: Busisness and Economy
Walking over: 1: Computers and Internet
Walking over: 2: Internet
Walking over: 2: WWW
Walking over: 2: Software
Walking over: 2: Games
Walking over: 1: Education
Walking over: 1: Entertainment
Walking over: 1: Science
Walking over: 2: Animals
Walking over: 2: Astronomy
Walking over: 3: Astronomers
Walking over: 3: Cosmology
Walking over: 4: Dark Matter
Walking over: 4: Research
Walking over: 2: Engineering