#[><>](https://esolangs.org/wiki/Fish), 46 + 3 for `-v` = 49 bytes


    0&>l?!v:f4*=?\l&:@+n$o!
      ^  o &+1n:&<
       ;n&<


This is an implementation of [xnor's algorithm](http://codegolf.stackexchange.com/a/92482/41881) in ><>.

It takes the input string on the stack (`-v` flag with the standard interpreter).

You can try it out on the [online interpreter](https://fishlanguage.com/playground).