int a;
void setup() {
  // put your setup code here, to run once:
pinMode(4, OUTPUT);
pinMode(3, OUTPUT);
pinMode(2, OUTPUT);
}

void loop() {
  // put your main code here, to run repeatedly:
for(a=1;a!=16;a++)
{digitalWrite(3, HIGH);
digitalWrite(2, HIGH);
digitalWrite(4, HIGH);
delay(1000);
digitalWrite(3, LOW);
digitalWrite(4, LOW);
digitalWrite(2, LOW);
delay(1000);
digitalWrite(2, LOW);
digitalWrite(3, HIGH);
digitalWrite(4, HIGH);
delay(1000);
digitalWrite(2, HIGH);
digitalWrite(3, LOW);
digitalWrite(4, HIGH);
delay(1000);
digitalWrite(2, LOW);
digitalWrite(3, HIGH);
digitalWrite(4, LOW);
delay(1000);}
}