Traceback (most recent call last):
  File "./prog.py", line 6, in <module>
    y = math.sqrt(float(x))
                    ~~~^^^
ValueError: could not convert string to float: ''

Traceback (most recent call last):
  File "./prog.py", line 6, in <module>
    y = math.sqrt(float(x))
                    ~~~^^^
ValueError: math domain error