const int buttonPin4 = 4;
const int ledPin3 = 10;
const int brightStep = 5; 
const int delayTime = 100;

int brightness = 0;

void setup() {
  // put your setup code here, to run once:
pinMode(8, OUTPUT);
pinMode(9, OUTPUT);
pinMode(ledPin3, OUTPUT);
pinMode(1, INPUT);
pinMode(2, INPUT);
pinMode(3, INPUT);
pinMode(buttonPin4, INPUT);
analogWrite(ledPin3, 0);
}

void loop() {
  // put your main code here, to run repeatedly:
  int button_value = digitalRead(1);
  int button_value2 = digitalRead(2);
  int button_value3 = digitalRead(3);
  int button_value4 = digitalRead(4);
  
  if (button_value == HIGH ){
      digitalWrite(8, HIGH);
  }
  else
      digitalWrite(8, LOW);
  
  if (button_value2 == HIGH ){
      digitalWrite(9, HIGH);
      delay (500);
      digitalWrite(9, LOW);
      delay (500);
  }
  
  if (button_value3 == HIGH ){
      digitalWrite(9, HIGH);
      delay (2000);
      digitalWrite(9, LOW);
      delay (2000);
  }

  if (button_value4 == HIGH ){
    for (int i = brightness; i <= 255; i+=brightStep){
      brightness = i;
      analogWrite(ledPin3, brightness);
      delay(delayTime);
    }
    for (int i = brightness; i >= 0; i-=brightStep){
      brightness = i;
      analogWrite(ledPin3, brightness);
      delay(delayTime);
    }
    delay(100);
    while (digitalRead(buttonPin4) == LOW){
      delay(10);
    }
  }
}