runtime error: exit status 2
output:
1166
1165
1168
panic: runtime error: index out of range [-81]

goroutine 1 [running]:
main.(*BIT).add(...)
	/tmp/build-4048780916/solution.go:119
main.main()
	/tmp/build-4048780916/solution.go:63 +0x6d4

exit status 1