void setup()
{
  int i;
  for(i=2;i<5;i++)
    pinMode(i,OUTPUT);
}
void loop()
{
 digitalWrite(2,HIGH);
 delay(3000);
 digitalWrite(3,HIGH);
 delay(2000);
 digitalWrite(3,LOW);
 digitalWrite(2,LOW);
 digitalWrite(4,HIGH);
 delay(4000);
 digitalWrite(4,LOW);
}