How to put 4 pictures together as 1 on an iPhone? (App)?

I have an app like picstitch that puts 4 separate pics together but it had borders between the pics and I hate that! I want it to look like one pic without any borders just together it takes so much time to do it on paint so if you know a app that does that without borders no lines and makes it look like one pic! Thanks so much I've been tryna to do 4 pics like that for Instagram!

You can try Aviary or Tadaa.