40. Construct a 16-input multiplexer from five 4-input multiplexers. Draw the 16-input multiplexer as a large block with 16 data lines labeled D0 through D15 and 4 select lines labeled S3 through S0. Inside the large block, draw each 4-input multiplexer as a small block with data lines D0 through D3 and select lines S1 and S0. Show the connections to the small blocks from the outside lines and the connections between the blocks to implement the big multiplexer. Explain the operation of your circuit.