int led1 = 3;
int led2 = 6;
int led3 = 11;

int brightness = 0;
int fadeAmount = 5;

// the setup routine runs once when you press reset:
void setup() {
  pinMode(led1, OUTPUT);
  pinMode(led2, OUTPUT);
  pinMode(led3, OUTPUT);

}

void loop() {
  analogWrite(led1, brightness);
  analogWrite(led2, brightness);
  analogWrite(led3, brightness);

  brightness = brightness + fadeAmount;

  if (brightness <= 0 || brightness >= 255) {
    fadeAmount = -fadeAmount;
  }
  delay(55);
}