#define BUTTON_PIN 4
int laststate = HIGH;

void setup() {
  Serial.begin(115200);
  pinMode(BUTTON_PIN, INPUT_PULLUP);
}

void loop() {
  int value=digitalRead((BUTTON_PIN));
  if (laststate != value) {
    laststate = value;
    if (value == HIGH) {
      Serial.println("released");
    }
    if (value == LOW) {
      Serial.println("pressed");
    }
    }
  }