int sw = 8;
int led = 9;
void setup() {
  Serial.begin(9600);
  pinMode(sw, INPUT_PULLUP);
  pinMode(led, OUTPUT);
}

void loop() {
  int val = digitalRead(sw);
  if(val==0){
    digitalWrite(led,1);
  }else{
    digitalWrite(led,0);;
  }
  delay(500);
}