int led = 3;
int brightness = 0;
int level = 0;

void setup() {
  // put your setup code here, to run once:
  pinMode(led, OUTPUT);
  Serial.begin(9600);
}

void loop() {
  // put your main code here, to run repeatedly:
  level = analogRead(A0);
  Serial.print("Light level in the room: ");
  Serial.print(level);
  Serial.print(". Light is ");

  if(level > 300) {
    Serial.print("on. Brightness: ");
    brightness = brightness +5;
    if(brightness > 255)
      brightness = 255;
  } else {
    Serial.print("off. Brightness: ");
    brightness = brightness - 5;
    if(brightness < 0)
      brightness = 0;
  }
  analogWrite(led, brightness);
  Serial.println(brightness);
}