char LED1 =0;
char LED2=1;
char LED3 =2;
char LED4=3;
void setup() {
  // put your setup code here, to run once:
pinMode(13, OUTPUT);
}

void loop() {
// put your main code here, to run repeatedly:
digitalWrite(13, HIGH);
delay(1000);
digitalWrite(13, LOW);
delay(1000);
}