70
1- (1-2) (3-4)
2- (3-4)
3- (2-3) (3-4) (6-7)
4- (4-5)
(2-3) (4-5) (5-6) (6-7)
5- (2-3) (4-5) (5-6)
(3-4) (5-6)
6- (2-3 ) (4-5) (5-6)
7- (2-3) (3-4) (4-5) (6-7)
(2-3)
8- (3-4) (4-5) ( 5-6) (6-7)
(2-3) (3-4) (4-5)(6-7)
9- (2-3) (4-5) (6-7)
10- (6-7)
11- (6-7 )