int button_state = 0;
void setup() {
  // put your setup code here, to run once:
  pinMode(2, OUTPUT);
  pinMode(0, OUTPUT);
  pinMode(16, INPUT_PULLUP);
}

void loop() {
  int button_state = digitalRead(16);
  if (button_state == LOW)
  {
    digitalWrite(2, HIGH);
    digitalWrite(0, LOW);  
  } 
  else
  {
  digitalWrite(2, LOW);
  digitalWrite(0, HIGH);
  }
}