code: public static int getYAsOppositeTileFormat(int zoom, int y) {
  		int tilesPerSide = tilesPerSide(zoom);
  		int oppositeY = tilesPerSide - y - 1;
  		return oppositeY;
  	}
docs: Get the standard y tile location as TMS or a TMS y location as standard
  
  @param zoom
  zoom level
  @param y
  y coordinate
  @return opposite tile format y