void setup()
{
  Serial.begin(9600);
  pinMode(13,OUTPUT); 
  pinMode(12,OUTPUT); 
  pinMode(11,OUTPUT);
}
	
void loop()
{
  char ch;
  if(Serial.available())
  {

  ch=Serial.read();
  Serial.print(ch);
  
  if(ch=='r'||ch=='R')
    {
      digitalWrite(13,HIGH);
      digitalWrite(12,LOW);
      digitalWrite(11,LOW);
    }

    else if(ch=='g'||ch=='G')
    {
      digitalWrite(13,LOW);
      digitalWrite(12,HIGH);
      digitalWrite(11,LOW);
    }

    else if(ch=='y' ||ch=='Y' )
    {
      digitalWrite(13,LOW);
      digitalWrite(12,LOW);
      digitalWrite(11,HIGH);

    }

  }

}