Flow diagrams provide a visual way of showing a process or algorithm:

• a box is used for an action
• a diamond (shaded) for making a decision
• arrows indicate the flow of control.

For example:

In the simple flow diagram above, if \(\text{A}\) was input as \(9\) it would be output as \(13\), whilst if it was input as \(11\) it would be unchanged and output as \(11\).

Now look at the following flow diagram:

What is the output if the input is \(77\)?