the world got obsess robotsand pace progress great Berlands programmer Draude decide build robot he work hard robot he teach walk short path point record movement like Draudes program bug robot do not walk short path Fortunately robot record movement correctly now Draude want find robot function wrong Heh Draude remember map field test robot easily robot walk right direction but field map lose find that s ask find exist map path record robot shortestthe map infinite checker field square contain obstruction it know robot try run obstruction by record robot movement find exist map possible choose robot start square start square robot move square movement coincide record one robot do not run move square path start square end shortestIn movement robot square provide obstrution square common side square robot currently