“…-9-class and 8-class: Original 50 classes of sequences are divided into 9 semantic categories [29,6] consisting of "boiling water" (8), "fire" (8), "flowers" (12), "fountains" (20), "plants" (108), "sea" (12), "smoke" (4), "water" (12), and "waterfall" (16), where the numbers in parentheses take account of sequences in each class. The "plants" category is eliminated from 9-class to form more challenging 8-class scheme [29,6].…”