Given the following program, choose the line necessary to replace the $***\text{'}$s so that the program segment will ensure that an illegal operation does not occur.

Write "Enter a number: $"$

Write "The square root of that number will be displayed."

Input MyNumber

$********************$

Write "The square root of $"+$ MyNumber

Write $"$is: $"+$ Sqrt$($MyNumber$)$ Else Write "Illegal operation!"

End If