You'll have to collect a pair of each numbers, letters or pictures.
Train your concentration and mind.
Do it day to day and check how many mistakes you do.
Try to decrease mistakes and time to open all cells.
Parameters
mset
Defines set of images. "n" - numbers (1..20); "a" characters (A..T); "p" - pictures. You can combine values to generate random set. Examples: mset=n -(only numbers); mset=np - (numbers or pictures).
Default: mset=nap