const int binaryPins[] = {10, 11, 12, 13};
const int addPins[] = {6, 7, 8, 9};
const int resultPins[] = {1, 2, 3, 4, 5};
int carrypin = 0;

void setup() {
  for (int i = 0; i < 4; i++) {
    pinMode(binaryPins[i], INPUT_PULLUP);
    pinMode(addPins[i], INPUT_PULLUP);
    pinMode(resultPins[i], OUTPUT);
  }
  pinMode(resultPins[4], OUTPUT);
  pinMode(carrypin,INPUT_PULLUP);
}

void loop() {

  bool carry = !digitalRead(carrypin);

  for (int i = 0; i < 4; i++) {
    bool a = digitalRead(binaryPins[i]) == LOW;
    bool b = digitalRead(addPins[i]) == LOW;
    bool c = a != b;
    bool s = c != carry;
    carry = a && b || c && carry;
    digitalWrite(resultPins[i], s ? LOW : HIGH);
  }

  digitalWrite(resultPins[4], carry ? LOW : HIGH);
}