panic: invalid argument to Intn

goroutine 1 [running]:
math/rand.(*Rand).Intn(0xfe960?, 0x4000074d80?)
	/usr/local/go/src/math/rand/rand.go:180 +0x64
main.generateCase(0x4000074ec8)
	/home/ubuntu/codeforces/0-999/700-799/700-709/706/verifierD.go:57 +0x248
main.main()
	/home/ubuntu/codeforces/0-999/700-799/700-709/706/verifierD.go:106 +0x18c
exit status 2