Display picture with different height? HTML

So I'm trying to insert pictures with different height next to eachother and under each other like this:

http://ift.tt/1BMmRnP

I know how to put them next to each other with the same height, but whenever I try to put them next to each other with different heights, IMG1's bottom line goes down to IMG4's bottom line. How do I make it like this?? Thank you!