const int btnPin=17;
const int ledPin=39;
void setup() {
  // put your setup code here, to run once:
  pinMode(btnPin,INPUT_PULLUP);
  pinMode(ledPin,OUTPUT);
  Serial.begin(9600);
}

void loop() {
  // put your main code here, to run repeatedly:
  Serial.println(digitalRead(btnPin));
  if(digitalRead(btnPin)==LOW) digitalWrite(ledPin,LOW);
  else digitalWrite(ledPin,HIGH);
}