const int fLed = 3;
const int sLed = 5;
const int tLed = 6;

int brightness = 0;
int increment = 1;

void setup() {
  // put your setup code here, to run once:

}

void loop() {
  // put your main code here, to run repeatedly:

  if(brightness > 255){
    increment = -1;
  }
  else if(brightness < 1){
    increment = 1;  
  }
  brightness = brightness +increment;

  analogWrite(fLed, brightness);
  analogWrite(sLed, brightness);
  analogWrite(tLed, brightness );
 
  delay(10);
  
}