The input stream of a stack is a list of all the elements we pushed onto the stack, in the order that we pushed them. The input stream is ABCDEFGHIJKLM.
The output stream is a list of all the elements that are popped off the stack, in the order that they are popped off.
a. What is the output stream of ABCDEFGHIJKLM?
b. If the input stream is ZYXWVUTSR, create a sequence of pushes and pops such that the output stream is YXVUWZSRT.
c. If the input stream is ZYXW, how many different output streams can be created?

well cos like a ds it doesn't really die out, unlike for example, fifa, they always come out with a new version, so lets say your fifa 18 is charging you to update the teams and stuff, so, if messi were to go to real madrid (never gonna happen) it would switch messi to the other team, until the owners of fifa come out with fifa 19, then the game would eventually stop updating, and back to the ds, it doesn't really stop working after sometime because there's lots of things that it could be used for, and idk if u know what i'm saying, but long story short, samsung, represents the ds, if they still work, and people love them but not the new version, the old version still works, so they don't really force people to buy new phones, get me?