int redLed = 9;
int greenLed = 10;
int analogPin = A3;
int switchPin = 8;
int val = 0;
int switchState = 0;

void setup() {
  pinMode(redLed, OUTPUT);
  pinMode(greenLed, OUTPUT);
  pinMode(switchPin, INPUT);
}

void loop() {
  val = analogRead(analogPin);
  int brightness = val / 4;
  int redMax = brightness;          
  int greenMax = 255 - brightness;  
  switchState = digitalRead(switchPin);

  if (switchState == HIGH) {  
    
    for (int i = 0; i <= 255; i++) {
      
      analogWrite(redLed, map(i, 0, 255, 0, redMax));
      analogWrite(greenLed, map(i, 0, 255, 0, greenMax));
      delay(4);
    }
    
    
    for (int i = 255; i >= 0; i--) {
      
      analogWrite(redLed, map(i, 0, 255, 0, redMax));
      analogWrite(greenLed, map(i, 0, 255, 0, greenMax));
      delay(4);
    }
  } else {
    
    analogWrite(redLed, redMax);
    analogWrite(greenLed, greenMax);
  }
}