oracle failed on case 4: runtime error: exit status 2
panic: runtime error: index out of range [-1]

goroutine 1 [running]:
main.main()
	/home/ubuntu/codeforces/1000-1999/1800-1899/1850-1859/1858/1858E2.go:55 +0x838

input:
30
+ 823087
?
?
- 1
+ 271532
?
?
- 1
+ 502854
!
- 1
+ 299092
?
+ 383245
+ 428792
+ 65818
+ 846157
!
- 1
+ 684478
+ 401696
!
!
+ 422002
?
!
+ 267953
!
?
- 1
exit status 1