Every 20MB of the file costs one credit. If the file size is less than 20M, it will be counted as 20M;
Every 100 pages of the file costs one credit. If the file is less than 100 pages, it will be counted as 100 pages.
(The above counting scheme takes its maximum value. For example, if the file size is 60M and the number of pages is 360, then counted as 360/100≈4, and it costs 4 credits)