panic: runtime error: index out of range [3] with length 3

goroutine 1 [running]:
main.pick(...)
	/src/programs/go/index_out_of_range.go:10
main.last(...)
	/src/programs/go/index_out_of_range.go:14
main.main()
	/src/programs/go/index_out_of_range.go:18 +0xb
exit status 2
