int x, y, z;

void setup() {
  z = 0;
  digitalWrite(2, z);
  y = analogRead(A0) / 512;
}

void loop() {
  x = analogRead(A0) / 512;
  if (x != y){
    delay(1);
    y = x;
    z = !z;
    digitalWrite(2, z);
  }
}