int reda=0;
int yellowa=1;
int greena=2;

int redb=3;
int yellowb=4;
int greenb=5;

int redc=6;
int yellowc=7;
int greenc=8;
void setup() {
  pinMode(reda, OUTPUT);
  pinMode(yellowa, OUTPUT);
  pinMode(greena, OUTPUT);

  pinMode(redb, OUTPUT);
  pinMode(yellowb, OUTPUT);
  pinMode(greenb, OUTPUT);

  pinMode(redc, OUTPUT);
  pinMode(yellowc, OUTPUT);
  pinMode(greenc, OUTPUT);
}

void loop() {
 digitalWrite(yellowb, LOW);
 digitalWrite(reda, HIGH);
   digitalWrite(greenb, HIGH);
   digitalWrite(redc, HIGH);
  delay(4000);

  digitalWrite(redc, LOW);
  digitalWrite(reda, LOW);
  digitalWrite(greenb, LOW);
  digitalWrite(yellowa, HIGH);
  digitalWrite(redb, HIGH);
  digitalWrite(redc, HIGH);
  delay(2000);

  digitalWrite(redc, LOW);
  digitalWrite(yellowa, LOW);
  digitalWrite(redb, LOW);
  digitalWrite(greena, HIGH);
  digitalWrite(redc, HIGH);
  digitalWrite(redb, HIGH);
  delay(4000);

digitalWrite(redc, LOW);
  digitalWrite(reda, LOW);
  digitalWrite(greena, LOW);
  digitalWrite(yellowc, HIGH);
  digitalWrite(redb, HIGH);
  digitalWrite(reda, HIGH);
  delay(2000);
digitalWrite(reda, LOW);
  digitalWrite(yellowc, LOW);
  digitalWrite(redb, LOW);
  digitalWrite(greenc, HIGH);
  digitalWrite(reda, HIGH);
  digitalWrite(redb, HIGH);
  delay(4000);

digitalWrite(greenc, LOW);
  digitalWrite(redb, LOW);
  digitalWrite(redc, HIGH);
  digitalWrite(yellowb, HIGH);
  delay(2000);      
       }