int led = 6;

void setup() {
  // put your setup code here, to run once:
  Serial.begin(9600);
  Serial.println("What LED do you want to light up?");
}

void loop() {
  // put your main code here, to run repeatedly:
  if(Serial.available()>0){
    led = Serial.parseInt();
    if (led!=0){
      for(int i = 2; i<7; i++){
        digitalWrite(i, LOW);
      }
    digitalWrite(led+1, HIGH);
    }
  }
  
  
}