For those objects that have multiple relations, how many images have a prediction class of "reading"?
prediction class of "reading" refers to PRED_CLASS = 'reading'; if two objects (OBJ1_SAMPLE_ID,
OBJ2_SAMPLE_ID) has
multiple PRED_CLASS_ID, it
means these two objects
have multiple relations;
SELECT COUNT(T1.IMG_ID) FROM IMG_REL AS T1 INNER JOIN PRED_CLASSES AS T2 ON T1.PRED_CLASS_ID = T2.PRED_CLASS_ID WHERE T2.PRED_CLASS = 'reading'
database name:db_id image_and_language
ATT_CLASSES table ATT_CLASSES Cols: ATTRIBUTE CLASS ID dtype integer, ATTRIBUTE CLASS dtype text, 
OBJ_CLASSES table OBJ_CLASSES Cols: OBJECT CLASS ID dtype integer, OBJECT CLASS dtype text, 
IMG_OBJ table IMG_OBJ Cols: IMAGE ID dtype integer, OBJECT SAMPLE ID dtype integer, OBJECT CLASS ID dtype integer, X dtype integer, Y dtype integer, W dtype integer, H dtype integer, 
IMG_OBJ_ATT table IMG_OBJ_ATT Cols: IMAGE ID dtype integer, ATTRIBUTE CLASS ID dtype integer, OBJECT SAMPLE ID dtype integer, 
PRED_CLASSES table PRED_CLASSES Cols: PREDICTION CLASS ID dtype integer, PREDICTION CLASS dtype text, 
IMG_REL table IMG_REL Cols: IMAGE ID dtype integer, PREDICTION CLASS ID dtype integer, OBJECT1 SAMPLE ID dtype integer, OBJECT2 SAMPLE ID dtype integer, 
