int a;int b;int c;

int S4=4;int S2=3;int S1=2;

void setup() {
  // put your setup code here, to run once:

for (int thisPin = 7; thisPin <= 13; thisPin++) {pinMode(thisPin, OUTPUT); }

pinMode(S4, INPUT);
pinMode(S2, INPUT);
pinMode(S1, INPUT);

for (int writelow = 7; writelow <= 13; writelow++) {digitalWrite(writelow, LOW);}

}

void loop() {
  // put your main code here, to run repeatedly:

if(digitalRead(S1) == HIGH){a = 1;}
else{a=0;}

if(digitalRead(S2) == HIGH){b = 1;}
else{b=0;}

if(digitalRead(S4) == HIGH){c = 1;}
else{c=0;}

int num = 14 - c*4 - b*2 - a;

for (int light = 7; light <= 13; light++) {
  if(num == light){digitalWrite(light, HIGH);}
  else{digitalWrite(light, LOW);}
}

}