int red = 13;
int pot = A0;
int potValue;

void setup() {
  pinMode(red, OUTPUT);
  pinMode(pot, INPUT);
  Serial.begin(9600);
}

void loop() {
  potValue = analogRead(pot);
  int brightness = map(potValue, 0, 1023, 0, 255);
  analogWrite(red, brightness);
  Serial.println(brightness);
  delay(10);
}