Answer: This answer is Negative 475.
Explanation: Look below for explanation.
The biggest city<span> in the </span>world<span> with 36.7 million inhabitants</span>
Okay so other ways to produce energy would be (just throwing out a few )
1 . Gum
2. Light (light wakes up your brain a proven fact)
3. Massage your ears (im serious it boost energy its proven)
4. Eat something whole grain
5. Listening to your favorite song
(Im serious for all these answers)
Hope I helped (: