here we have this screen AAC and then we see out in the past AAC occurred so let's just store the index into the past so this occurred one two three times steps into the past so let's just store this number three in the past and then we we also add into the next character which is B so that's that's basically how this works at this point C we see oh there's a string CAE in the future but of that string occurred in the past so let's just store the number three which indicates that you just need to jump three into the past to just copy that