2. Sketch the symbols and constructs used in NS diagrams.
3. List three disadvantages of using NS diagrams.
4. Draw a Nassi-Schneiderman diagram for the following problem:
You are a rat-catcher for the House of Parliament and each evening you set a number of rat-traps around the House. Each morning at 6.00 a.m. you walk around the traps to see what rats have been caught, to clear the traps if a rat is caught in a trap, and to count of the number of rats which were caught.