panic: invalid argument to Intn

goroutine 1 [running]:
math/rand.(*Rand).Intn(0x129b48?, 0x40000b20e0?)
	/usr/local/go/src/math/rand/rand.go:180 +0x64
main.generate()
	/home/ubuntu/codeforces/1000-1999/1800-1899/1850-1859/1851/verifierE.go:47 +0x13c
main.main()
	/home/ubuntu/codeforces/1000-1999/1800-1899/1850-1859/1851/verifierE.go:89 +0x114
exit status 2