int button = 4;

int lastState = 0;
int currentState = 0;

void setup() {
  // enable serial communication
  Serial.begin(9600);

  pinMode(4, INPUT);

}

void loop() {
  currentState = digitalRead(4);

  if(currentState != lastState)
  {
    if(currentState == 1)
    {
      Serial.write("1");
    }
    else if(currentState == 0)
    {
      Serial.write("0");
    }
    //Serial.write(currentState);
  }
  lastState = currentState;
}