#define LED1 4
#define LED2 5
#define LED3 6
void setup() 
{
  pinMode(LED1,OUTPUT);
  pinMode(LED2, OUTPUT);
  pinMode(LED3, OUTPUT);
}

void loop() 
{
 digitalWrite(LED1, HIGH);
 digitalWrite(LED2, LOW);
 digitalWrite(LED3, LOW);
 delay(1000);
 digitalWrite(LED1, HIGH);
 digitalWrite(LED1,LOW);
 digitalWrite(LED2,HIGH);
 digitalWrite(LED3,LOW);
 delay(1000);
 digitalWrite(LED1,LOW);
 digitalWrite(LED2, LOW);
 digitalWrite(LED3, HIGH);
delay(1000);
 }