panic: invalid argument to Intn goroutine 1 [running]: math/rand.(*Rand).Intn(0x400006ceb0?, 0xffff9cfa6150?) /usr/local/go/src/math/rand/rand.go:180 +0x64 main.genCase(0x400006ceb0) /home/ubuntu/codeforces/1000-1999/1600-1699/1680-1689/1682/verifierF.go:79 +0x308 main.main() /home/ubuntu/codeforces/1000-1999/1600-1699/1680-1689/1682/verifierF.go:138 +0x28c exit status 2