Read the dialogue and comprehend it. Answers of the questions below based on the dialogue.
 

Udin: "I want to tell how our class won the First Prize of the Classroom Competition."

Lina: "Let's guide Udin to tell how our class won the First Prize of the Classroom Competition. How did you know the Classroom Competition?"

Udin: "The principal announced the Classroom Competition on Monday in the flag ceremony."

Edo: Okay. What did you do then?"

Udin: When we were back to the classroom, we realised that many desks and chairs are old and dirty. Some had loose legs"

Lina: "And then?"

Udin: "In the afternoon, we talked and agreed to come on Saturday to fix them"

Lina: "What did we bring to work on Saturday?"

Udin: "On Saturday, each of us brought something from home, like soap, cloth, a broom, a mop, nails, a hammer, a duster, and so on."

Edo: "What did the students do with the desks and chairs?"

Udin: "Some of us washed the desks and the chairs. Some furnished them. Some fix the legs."

Lina: "So, we won the competition!"

Udin: "Yes. Now our desks and chairs are clean and strong. And we won the First Prize of the Classroom Competition."

How did the students know about the competition?