const int buttonPin = 15;  // pin push button
const int ledPin = 5;      // pin LED

void setup() {
  pinMode(ledPin, OUTPUT);
  pinMode(buttonPin, INPUT_PULLDOWN); 
}

void loop() {
  if (digitalRead(buttonPin) == HIGH) {  
    digitalWrite(ledPin, HIGH);          
  } else {                              
    digitalWrite(ledPin, LOW);           
  }
}