A class has a total of 16 students., and their ranks in Mathematics and Physics are as given below. The two numbers that are within the brackets are used to indicate the ranks of these 16 students Mathematics and Physics.

(1, 1) (2,10) (3,3) (4,4) (5,5) (6,7) (7,2) (8,6) (9,8)

(10,11) (11, 15) (12,9) (13,14) (14,12) (15,16) (16,13).The rank correlation coefficient for the abilities of this class in Mathematics and Physics is: