void setup() {
  pinMode(9, OUTPUT);//define pin(PWM Pin)
  Serial.begin(9600);//serial monitor enable
}
void loop() {
  int brightness;//naming the veriable
  brightness = analogRead(A0);//Put the analog read value into the veriable
  brightness = map(brightness, 0, 1023, 0 , 255);//0-1023 to 0-255
  analogWrite(9, brightness);//led on and off
  Serial.println(brightness);//print serial monitor value
}