int led1 = 13; 
//int led2=12;
//int led3=11;
void setup() {
  pinMode(led1, OUTPUT); 
 // pinMode(led2, OUTPUT); 
  //pinMode(led3, OUTPUT); 
}

void loop() {
  digitalWrite(led1, HIGH);  
  delay(2000);               
  digitalWrite(led1, LOW);  
  delay(2000);   
  //digitalWrite(led2, HIGH);  
  //delay(2000);               
  //digitalWrite(led2, LOW);  
  //delay(0);   
  //digitalWrite(led3, HIGH);  
  //delay(2000);               
  //digitalWrite(led3, LOW);  
  //delay(0);        
}