#define S1 2
#define S2 4
#define S3 7
#define S4 8
#define P1 10

bool S1_h, S2_h, S3_h, S4_h;

void setup() {
  // put your setup code here, to run once:
pinMode(S1,INPUT_PULLUP);
pinMode(S2,INPUT_PULLUP);
pinMode(S3,INPUT_PULLUP);
pinMode(S4,INPUT_PULLUP);
pinMode(P1,OUTPUT);
}

void loop() {
  //Eingangsabbild
S1_h = !digitalRead(S1);
S2_h = !digitalRead(S2);
S3_h = !digitalRead(S3);
S4_h = !digitalRead(S4);
  // put your main code here, to run repeatedly:
if ((S1_h && S2_h && S3_h && !S4_h)||(S1_h && S2_h && !S3_h && !S4_h) ||(S1_h && !S2_h && S3_h && !S4_h)||(!S1_h && S2_h && S3_h && !S4_h)||(S1_h && !S2_h && !S3_h && S4_h)||(!S1_h && S2_h && !S3_h && S4_h) )
 {digitalWrite(P1,HIGH);
 }

else
{
digitalWrite(P1,LOW);
}
}//ende loop