#define S0 2
#define Led_Gruen 11

unsigned long startwert;
bool Flag=0, S0_h;


void setup() {
  // put your setup code here, to run once:
  pinMode(S0, INPUT_PULLUP);
  pinMode(Led_Gruen, OUTPUT);

}

void loop() {
// Eingänge einlesen und invertieren (wegen Pullup)
S0_h = !digitalRead(S0);


  if(S0_h)
 {
  if(Flag ==0)
  {
    startwert=millis();
    Flag=1;
  }
 }
 else if(!S0_h)
     Flag=0;


  if((millis()-startwert>= 4000) and S0_h) 
      digitalWrite(Led_Gruen,HIGH);
  else if(!S0_h)
  {
    digitalWrite(Led_Gruen,LOW);
    startwert = millis();

  }
      
}