Answer:
The complete program is as follows:
m_str = input('Input m: ')
mass = float(m_str)
e = mass * 300000000**2
print("e = ",e)
Step-by-step explanation:
This is an unchanged part of the program
m_str = input('Input m: ')
This converts m_str to float
mass = float(m_str)
This calculates the energy, e
e = mass * 300000000**2
This is an unchanged part of the program
print("e = ",e)