#define LED1 4
#define SW1 5
void setup() {
  // put your setup code here, to run once:
  pinMode(LED1,OUTPUT);
  pinMode(SW1, INPUT_PULLUP);
}

void loop() {
  if(digitalRead(SW1)==0){
    digitalWrite(LED1,HIGH);
    delay(250);
    digitalWrite(LED1,LOW);
    delay(250);
  }
  
}