Multi Command Block Teleportation

I'm trying to make it so at the push of a button every player standing at the spawn (Location X: 0, Y: 100, Z: 0) would be teleported to each corner on the map. I know its possible to do with just 1, 2, 3, 4 (set number of people) etc.. But what I want to do is teleport any random number of players that happens to be playing the map divided into each corner (I know that if it wasn't even that I would just have one group with one more player, thats fine) I really cannot find a way to make each player depending on how many players there are to be evenly teleported towards the 4 provided locations. Note: It's a modless Minecraft server with these people on it.
1= X: 102, Y: 62, Z: 108.
2= X: 102, Y: 62, Z: -108.
3= X: 318, Y: 62, Z: -108.
4= X: 318, Y: 62, Z: 108.
If this isn't possible I think this should be something Mojang would have to add to Minecraft for sure. If it was added it would be something like /tp divide @a [x1y1z1,x2y2z,x3y3z3]