void setup() 
{
  pinMode(15, OUTPUT);//R1
  pinMode(2, OUTPUT);//Y1
  pinMode(4, OUTPUT);//G1
  pinMode(5, OUTPUT);//R2
  pinMode(18, OUTPUT);//Y2
  pinMode(19, OUTPUT);//G2
}

void loop() 
{
  digitalWrite(15, HIGH);      
  digitalWrite(2, LOW);   
  digitalWrite(4, LOW);  
  digitalWrite(5, LOW);      
  digitalWrite(18, LOW);   
  digitalWrite(19, HIGH);  
  delay(5000);  
  digitalWrite(15, HIGH);      
  digitalWrite(2, LOW);   
  digitalWrite(4, LOW);  
  digitalWrite(5, LOW);      
  digitalWrite(18, HIGH);   
  digitalWrite(19, LOW);   
  delay(2000); 
  digitalWrite(15, LOW);      
  digitalWrite(2, LOW);   
  digitalWrite(4, HIGH);  
  digitalWrite(5, HIGH);      
  digitalWrite(18, LOW);   
  digitalWrite(19, LOW);    
  delay(5000);      
  digitalWrite(15, LOW);      
  digitalWrite(2, HIGH);   
  digitalWrite(4, LOW);  
  digitalWrite(5, HIGH);      
  digitalWrite(18, LOW);   
  digitalWrite(19, LOW);    
  delay(2000); 
  digitalWrite(15, HIGH);      
  digitalWrite(2, LOW);   
  digitalWrite(4, LOW);  
  digitalWrite(5, LOW);      
  digitalWrite(18, LOW);   
  digitalWrite(19, HIGH);    
  delay(2000);       
}