#Pyth, 8 bytes
<z+1/lz2
Not the shortest Pyth answer (by half) but I'm making an effort to learn the language and this is my first post using it (I'm Java/Python/Lotus==vervose background). Posted as much for comments and feedback as anything. It's also the first Pyth program that I have actually got to work :)
Now I just need to work out how the 4 byte answer from @Maltysen works :-)