How to determine the size of an attached file from a IMAP message

FETCH 20 BODYSTRUCTURE

20 FETCH (BODYSTRUCTURE (("TEXT" "PLAIN" ("CHARSET" "ISO-8859-15" "FORMAT" "flowed") NIL NIL "8BIT" 950 30 NIL NIL NIL)("IMAGE" "JPEG" ("NAME" "r001-023.jpg") NIL NIL "BASE64" 1708116 NIL ("INLINE" ("FILENAME" "r001-023.jpg")) NIL)("IMAGE" "JPEG" ("NAME" "r001-022.jpg") NIL NIL "BASE64" 2077114 NIL ("INLINE" ("FILENAME" "r001-022.jpg")) NIL)("IMAGE" "JPEG" ("NAME" "r001-012.jpg") NIL NIL "BASE64" 2374832 NIL ("INLINE" ("FILENAME" "r001-012.jpg")) NIL) "MIXED" ("BOUNDARY" "------------090105040606010906000608") NIL NIL))