Given a list of cities, determine the closest one to the equator.
Madrid, Cairo, Beijing, Tokyo
The closest city to the equator from the list (Madrid, Cairo, Beijing, Tokyo) is Cairo.
Complete the following task based on the instruction and optional input provided.### Instruction:
Given a list of cities, determine the closest one to the equator.

### Input:
Madrid, Cairo, Beijing, Tokyo

### Output:
The closest city to the equator from the list (Madrid, Cairo, Beijing, Tokyo) is Cairo.