test 1 failed: runtime error: exit status 2
panic: runtime error: index out of range [4] with length 4

goroutine 1 [running]:
main.build(0x19b920?, 0x4000022060?, 0x4000076cb8?)
	/tmp/build-1848710654/solution.go:20 +0xe0
main.build(0x4000076ce8?, 0xb03a4?, 0x0)
	/tmp/build-1848710654/solution.go:25 +0xa4
main.build(0x10f058?, 0x40000641e0?, 0x0)
	/tmp/build-1848710654/solution.go:25 +0xa4
main.solve()
	/tmp/build-1848710654/solution.go:139 +0x2fc
main.main()
	/tmp/build-1848710654/solution.go:200 +0x1c