Design an algorithm to calculate the average of three numbers.
Here is a simple algorithm to calculate the average of three numbers:

1. Start
2. Define a variable `sum` and set it to 0
3. Input the first number and store it in the variable `num1`
4. Input the second number and store it in the variable `num2`
5. Input the third number and store it in the variable `num3`
6. Add `num1`, `num2`, and `num3` and store the result in the variable `sum`
7. Divide `sum` by 3 to calculate the average of the three numbers
8. Output the result
9. End.
Below is an instruction that describes a task, write a response that appropriately completes the request.

### Instruction:
Design an algorithm to calculate the average of three numbers.

### Response:
Here is a simple algorithm to calculate the average of three numbers:

1. Start
2. Define a variable `sum` and set it to 0
3. Input the first number and store it in the variable `num1`
4. Input the second number and store it in the variable `num2`
5. Input the third number and store it in the variable `num3`
6. Add `num1`, `num2`, and `num3` and store the result in the variable `sum`
7. Divide `sum` by 3 to calculate the average of the three numbers
8. Output the result
9. End.