int delaytime=500;
void setup()
{
  pinMode(0, OUTPUT);    
  pinMode(1, OUTPUT);    
  pinMode(2, OUTPUT);  
}
void loop() {  
    digitalWrite(0,1);
    delay(delaytime);
    digitalWrite(0,0);
    delay(delaytime);
    digitalWrite(1,1);
    delay(delaytime);
    digitalWrite(1,0);
    delay(delaytime);
    digitalWrite(2,1);
    delay(delaytime);
    digitalWrite(2,0);
    delay(delaytime);
  }