Director Zhang is sorting the last three programs of the party. Adjacent programs cannot belong to the same category. Director Zhang should choose from three sketch programs, three song programs and three dance programs. To arrange the last three programs, the following conditions should be met: if the first program is sketch, the second program is dance, and if the second program is song, The first program is dance. If the third program is sketch or dance, the second program is song.
the possible sequence of program arrangement?
Program 1: Dance program 2: Sketch program 3: Song