#define S1 7
#define S2 4
#define S3 2
#define V1 8

bool S1_h, S2_h, S3_h;

void setup() {
  // put your setup code here, to run once:
pinMode(S1,INPUT_PULLUP);
pinMode(S2,INPUT_PULLUP);
pinMode(S3,INPUT_PULLUP);
pinMode(V1,OUTPUT);

}

void loop() {
    //Eingangsabbild
S1_h = !digitalRead(S1);
S2_h = !digitalRead(S2);
S3_h = !digitalRead(S3);
  // put your main code here, to run repeatedly:

  if ( S1_h && S2_h && S3_h )
 {digitalWrite(V1, HIGH);
 }
 else
 {
digitalWrite(V1, LOW);
 }
}//end loop