[ruby] How to get the last element of an array in Ruby?

Example:

a = [1, 3, 4, 5]
b = [2, 3, 1, 5, 6]

How do I get the last value 5 in array a or last value 6 in array b without using a[3] and b[4]?

One other way, using the splat operator:

*a, last = [1, 3, 4, 5]

STDOUT:
a: [1, 3, 4]
last: 5