const int Leds[]={8,6,4,2};
const int LED=4;

void setup() {
  // put your setup code here, to run once:
  Serial1.begin(9600);
  Serial1.println("Hello, Raspberry Pi Pico!");
  for(int i=0;i<LED;i++){
    pinMode(Leds[i],OUTPUT);
  }
}

void loop() {
  if(Serial1.available()>0){
    int userInput=Serial1.parseInt();
    if(userInput>=1 && userInput<=LED){
      for(int i=0;i<LED;i++){
        digitalWrite(Leds[i],LOW);
      }
      digitalWrite(Leds[userInput-1],HIGH);
      Serial1.print(userInput);
      Serial1.println("ON");
    }
  }
}