int R = 6;
int G = 3;
int B = 5;
char data;

void setup() {
  // put your setup code here, to run once:
  Serial.begin(9600);
  pinMode(R, OUTPUT);
  pinMode(G, OUTPUT);
  pinMode(B, OUTPUT);
  Serial.println("the program is live!");
}

void loop() {
  if(Serial.available() > 0){
    data = Serial.read();
    Serial.println(data);
    if(data == 'R'){
    analogWrite(R,255);
    analogWrite(G,0);
    analogWrite(B,0);
    }
    if(data == 'G'){
    analogWrite(R,0);
    analogWrite(G,255);
    analogWrite(B,0);
    }
    if(data == 'B'){
    analogWrite(R,0);
    analogWrite(G,0);
    analogWrite(B,255);
    }
  }
}