60. On the blackboard, there is a sequence of numbers: $1,2,3, \cdots, 2018,2019$, and you can arbitrarily erase several numbers and write down the remainder of the sum of the erased numbers divided by 17 (write 0 if it is exactly divisible). Continue this operation until only one number remains on the blackboard, this number is ـ. $\qquad$
Reference answer: 6
Exam point: Operations and strategies