Thank for you help, fang. But I just found that the code is more complicate that I imagine
It looks like this
http://photos-c.ak.fbcdn.net/photos-ak-snc1/v1979/87/20/1534977624/n1534977624_1886354_8 ...
http://photos-h.ak.fbcdn.net/photos-ak-snc1/v1979/87/20/1534977624/n1534977624_1885207_9634.jpg
The pattern is composed of 4 digits, we need to answer the number which color is different from other 3 ...
The mud I am playing have a code like this
http://photos-h.ak.fbcdn.net/photos-ak-snc1/v1979/87/20/1534977624/a1534977624_1885207_9634.jpg
It requires us to answer 7 to continue playing, how to read ...