#define red 13
#define green 11
#define blue 7
#define yellow 2
char x;
void setup()
{
     Serial.begin(9600);
     Serial.println("Enter a Value : ");
     pinMode(red, OUTPUT); 
     pinMode(green, OUTPUT); 
     pinMode(blue,OUTPUT); 
    pinMode(yellow, OUTPUT);
}


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

        if (x=='r')
            digitalWrite(red,HIGH);
        if (x=='g')
            digitalWrite(green,HIGH);
        if (x=='b')
            digitalWrite(blue,HIGH);  

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

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