const int add = 19;
const int minus = 18;
const int in1[] = {5, 21, 22, 23};
const int in2[] = {0, 4, 16, 17};
const int out[] = {32, 33, 25, 26, 27};
const int led[] = {32, 33, 25, 26, 27, 0, 4, 16, 17, 5, 21, 22, 23, 18, 19};

long a, b, op, answer;

void setup() {
  Serial.begin(115200);
  for(int i = 0; i < 15; i++){
    pinMode(led[i], OUTPUT);
  }
}

void number1(int num){
  for(int i = 3; i >= 0; i--){
    digitalWrite(in1[i], (num & (1 << i)) ? HIGH : LOW);
  }
}

void number2(int num){
  for(int i = 3; i >= 0; i--){
    digitalWrite(in2[i], (num & (1 << i)) ? HIGH : LOW);
  }
}

void outled(int num){
  for(int i = 4; i >= 0; i--){
    digitalWrite(out[i], (num & (1 << i)) ? HIGH : LOW);
  }
}

void loop() {
  Serial.print("Input 1: ");
  while(Serial.available() == 0){
  }
  a = Serial.readString().toInt();
  Serial.println(a);
  number1(a);
  Serial.print("Input 2: ");
  while(Serial.available() == 0){
  }
  b = Serial.readString().toInt();
  Serial.println(b);

  number2(b);

  Serial.print("(1) Addition \n(2) Subtraction \nOperation: ");
  while(Serial.available() == 0){
  }
  op = Serial.readString().toInt();
  Serial.println(op);

  if (op == 1) {
    digitalWrite(add, HIGH);
    answer = a + b;
  }
  else {
    digitalWrite(minus, HIGH);
    if (a > b) {
      answer = a - b;
    }
    else {
      answer = b - a;
    }
  }
  Serial.print("Answer = ");
  Serial.println(answer);
  outled(answer);
  delay(10000);
  for(int i = 0; i < 15; i++){
    digitalWrite(led[i], LOW);
  }//checked822
}