bool button, statusLed = 0;

void setup() {
  pinMode(25, INPUT_PULLUP);
  pinMode(26, OUTPUT);
  Serial.begin(9600);
}

void loop() {
  button = digitalRead(25);

  if (button == 0) {
    if (statusLed == 0) {
      statusLed = 1;
    }
    else {
      statusLed = 0;
    }
  }

  digitalWrite(26, statusLed);
  Serial.println(button);
  delay(500);
}