1;1 3;3 7;7 2;3 6;5
2 3 5 6 8 9 ? ?
In series 6,4,1,2,2,8,7,4,2,1,5,3,8,6,2,1,7,1,4,1,3,2,8,7,6, how many pairs of successive numbers have a difference of 1 each?