int LED1=13; 
int LED2=10; 
int LED3=7; 
void setup() 
{
 pinMode(13,OUTPUT);
 pinMode(10, OUTPUT);
 pinMode(7, OUTPUT);
 digitalWrite(13, HIGH);
 digitalWrite(10, LOW);
 digitalWrite(7, LOW);
 delay(4000);
 digitalWrite(13, LOW);
 digitalWrite(10, HIGH); // put your setup code here, to run once:
 digitalWrite(7, LOW);
 delay(4000);
 digitalWrite(13, LOW);
 digitalWrite(10, LOW);
 digitalWrite(7, HIGH);
 delay(4000);
}


void loop() {
  // put your main code here, to run repeatedly:

}