const int LED = 1;
const int btn = 0;
int btnState = 0;

void setup() {
  pinMode(LED, OUTPUT);
  pinMode(btn, INPUT_PULLUP);
}

void loop() {
  btnState = digitalRead(btn);
  if (btnState == LOW)
  {
    digitalWrite(LED, HIGH);
  } 
  else{
    digitalWrite(LED, LOW);
  }
  delay(10);
}