Read this excerpt from a short story. Liam navigated the busy park, scanning the crowd for his friends. They had agreed to meet at the water slide, and soon the towering steps came into view. He spotted Rachel and Marco by the inner tubes, and soon the three were racing to the top of the slide. There were over a hundred wooden stairs to climb, but the friends usually climbed them without pause. This time, however, their progress was slowed by a surprising mid-day crowd. Spiraling up the stairs were dozens of eager park patrons, each gripping a slippery tube. Liam shook his head and told his friends they would need a little more patience than usual waiting for their favorite view from the top. What complication is introduced in the excerpt?