#define LED 13
#define BUTTON_ON 8
#define BUTTON_OFF 4
#define BUTTON_BLINK 2

void setup() {
  // put your setup code here, to run once:
  pinMode(BUTTON_ON, INPUT);
  pinMode(BUTTON_OFF, INPUT);
  pinMode(BUTTON_BLINK, INPUT);
  pinMode(LED, OUTPUT);
}

void loop() {
  // put your main code here, to run repeatedly:
  if(digitalRead(BUTTON_ON) == HIGH)
    digitalWrite(LED, HIGH);

  if(digitalRead(BUTTON_OFF) == HIGH)  
    digitalWrite(LED, LOW);

  if(digitalRead(BUTTON_BLINK) == HIGH)
  {
    digitalWrite(LED, HIGH);
    delay(500);
    digitalWrite(LED, LOW);
    delay(500);
  }
}