func GenerateRandomInt64(min, max int64) int64 {
	upper := max - min

	nBig, err := rand.Int(rand.Reader, big.NewInt(upper))

	if err != nil {
		panic(err)
	}

	return nBig.Int64() + min
}
func GenerateRandomInt64(min, max int64) int64 {
	upper := max - min

	nBig, err := rand.Int(rand.Reader, big.NewInt(upper))

	if err != nil {
		panic(err)
	}

	return nBig.Int64() + min
}
func GenerateRandomInt64 ( min , max int64 ) int64 { upper := max - min nBig , err := rand . Int ( rand . Reader , big . NewInt ( upper ) ) if err != nil { panic ( err ) } return nBig . Int64 ( ) + min }
// Generate random number in [0,n)
Generate random number in [ 0 n )