int r1=3;
int r2=4;
int g1=5;
int g2=6;
int y1=7;
int y2=8;
void setup()
{
  pinMode(r1, OUTPUT);
  pinMode(r2, OUTPUT);
  pinMode(g1, OUTPUT);
  pinMode(g2, OUTPUT);
  pinMode(y1, OUTPUT);
  pinMode(y2, OUTPUT);
}
void loop()
{
  digitalWrite(r1, HIGH);
  digitalWrite(r2, LOW);
  digitalWrite(g1,LOW);
  digitalWrite(g2, HIGH);
  digitalWrite(y1, LOW);
  digitalWrite(y2, LOW);
  delay(2000);
   digitalWrite(r1, LOW);
  digitalWrite(r2, LOW);
  digitalWrite(g1,LOW);
  digitalWrite(g2, LOW);
  digitalWrite(y1, LOW);
  digitalWrite(y2, HIGH);
  delay(2000);
   digitalWrite(r1, LOW);
  digitalWrite(r2, HIGH);
  digitalWrite(g1,HIGH);
  digitalWrite(g2, LOW);
  digitalWrite(y1, LOW);
  digitalWrite(y2, LOW);
  delay(2000);
   digitalWrite(r1, LOW);
  digitalWrite(r2, LOW);
  digitalWrite(g1,LOW);
  digitalWrite(g2, LOW);
  digitalWrite(y1, HIGH);
  digitalWrite(y2, LOW);
  delay(2000);
  
}