bool led_flag = 0;
bool bat;
bool flag = 0;
void setup() {
  pinMode(3, INPUT_PULLUP);
  pinMode(9, OUTPUT);
}
void loop() {
  bat = !digitalRead(3);
  if (flag == 1 && bat == 0 && millis() > 30){
    led_flag = !led_flag;
    flag = 1;
    digitalWrite(9, led_flag);
  }
  if (flag == 0 && bat == 1 && millis()>30) {
    led_flag = !led_flag;
    flag = 0;
    digitalWrite(9, led_flag);
    delay(30);
  }
}