void setup()
{
  for(int i=2;i<=7;i++){
    pinMode(i, OUTPUT);
  }
}

void loop()
{
  // Step 1
  digitalWrite(2,1);//R1
  digitalWrite(3,0);
  digitalWrite(4,0);
  digitalWrite(5,0);
  digitalWrite(6,0);
  digitalWrite(7,1);//G2
  delay(15000);
  // Step 2
  digitalWrite(2,1);//R1
  digitalWrite(3,0);
  digitalWrite(4,0);
  digitalWrite(5,0);
  digitalWrite(6,1);//Y2
  digitalWrite(7,0);
  delay(5000);
  // Step 3
   digitalWrite(2,0);
  digitalWrite(3,0);
  digitalWrite(4,1);//G1
  digitalWrite(5,1);//R2
  digitalWrite(6,0);
  digitalWrite(7,0);
  delay(15000);
  // step 4
   digitalWrite(2,0);
  digitalWrite(3,1);//Y1
  digitalWrite(4,0);
  digitalWrite(5,1);//R2
  digitalWrite(6,0);
  digitalWrite(7,0);
  delay(5000);
 
  
}