#define red 13
#define green  10
#define yellow 9
#define blue 7
char x;
void setup() 
{
  
Serial.begin(9600);
pinMode(red, OUTPUT);
pinMode(green, OUTPUT);

pinMode(yellow, OUTPUT);
pinMode(blue, OUTPUT);

Serial.println("Enter a value : ");



}

void loop() 
{

if(Serial.available()>0)
{
  x=Serial.read();

if(x=='r')
 digitalWrite(red, HIGH);

if(x=='g')
 digitalWrite(green, HIGH);

if(x=='y')
 digitalWrite(yellow, HIGH);

 if(x=='b')
digitalWrite(blue, HIGH);
}


if(x=='o')
{
digitalWrite(red, LOW);
digitalWrite(green, LOW);
digitalWrite(yellow, LOW);
digitalWrite(blue, LOW);

}

}