const int buttonPin = A0;  // the number of the pushbutton pin
const int ledPin = 13;    // the number of the LED pin

void setup() {
  // put your setup code here, to run once:
  pinMode(ledPin, OUTPUT);
  pinMode(buttonPin, INPUT);

}

void loop() {
  // put your main code here, to run repeatedly:
buttonState = analogRead((buttonPin));

  // check if the pushbutton is pressed. If it is, the buttonState is HIGH:
  if (buttonState == HIGH) {
    // turn LED on:
    digitalWrite(ledPin, HIGH);
  } else {
    // turn LED off:
    digitalWrite(ledPin, LOW);
}