#define led1 5
#define led2 6
#define led3 4
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,LOW);
  digitalWrite(led2, HIGH);
  digitalWrite(led3,LOW);
  delay(1000);
  digitalWrite(led1,LOW);
  digitalWrite(led2,LOW);
  digitalWrite(led3,HIGH);
  delay(1000);
}