const int Red= 10;
const int Green= 7;
const int Blue= 4;
void setup() {
  pinMode(Red, OUTPUT);
  pinMode(Green, OUTPUT);
  pinMode(Blue, OUTPUT);
}

void loop() {
  //red.
  analogWrite(Red,255);
  analogWrite(Green,0);
  analogWrite(Blue,0);
  delay(500);
  //green.
  analogWrite(Red,0);
  analogWrite(Green,255);
  analogWrite(Blue,0);
  delay(500);
  //blue.
  analogWrite(Red,0);
  analogWrite(Green,0);
  analogWrite(Blue,255);
  delay(500);
  //YELLOW.
  analogWrite(Red,255);
  analogWrite(Green,255);
  analogWrite(Blue,0);
  delay(500);
}