#define r1 9
#define r2 8
#define r3 7
#define r4 6
#define c1 5
#define c2 4
#define c3 3
#define c4 2
int cal1;
int cal2;
int cal3;
int cal4;

void setup() {
  pinMode(r1, OUTPUT);
  pinMode(r2, OUTPUT);
  pinMode(r3, OUTPUT);
  pinMode(r4, OUTPUT);
  pinMode(c1, INPUT);
  pinMode(c2, INPUT);
  pinMode(c3, INPUT);
  pinMode(c4, INPUT);
  Serial.begin(115200);
  digitalWrite(c1, 1);
  digitalWrite(c2, 1);
  digitalWrite(c3, 1);
  digitalWrite(c4, 1);
}
void loop() {
  /***********************1-A******************************/
  digitalWrite(r1, 0);
  digitalWrite(r2, 1);
  digitalWrite(r3, 1);
  digitalWrite(r4, 1);
  cal1 = digitalRead(c1);
  cal2 = digitalRead(c2);
  cal3 = digitalRead(c3);
  cal4 = digitalRead(c4);

  if (cal1 == 0) {
    Serial.println("1");
    delay(200);
  }
  else if (cal2 == 0) {
    Serial.println("2");
    delay(200);
  }

  else if (cal3 == 0) {
    Serial.println("3");
    delay(200);
  }
  else if (cal4 == 0) {
    Serial.println("A");
    delay(200);
  }
   /***********************4-B******************************/
  digitalWrite(r1, 1);
  digitalWrite(r2, 0);
  digitalWrite(r3, 1);
  digitalWrite(r4, 1);
  cal1 = digitalRead(c1);
  cal2 = digitalRead(c2);
  cal3 = digitalRead(c3);
  cal4 = digitalRead(c4);

  if (cal1 == 0) {
    Serial.println("4");
    delay(200);
  }
  else if (cal2 == 0) {
    Serial.println("5");
    delay(200);
  }

  else if (cal3 == 0) {
    Serial.println("6");
    delay(200);
  }
  else if (cal4 == 0) {
    Serial.println("B");
    delay(200);
  }
   /***********************7-C******************************/
  digitalWrite(r1, 1);
  digitalWrite(r2, 1);
  digitalWrite(r3, 0);
  digitalWrite(r4, 1);
  cal1 = digitalRead(c1);
  cal2 = digitalRead(c2);
  cal3 = digitalRead(c3);
  cal4 = digitalRead(c4);

  if (cal1 == 0) {
    Serial.println("7");
    delay(200);
  }
  else if (cal2 == 0) {
    Serial.println("8");
    delay(200);
  }

  else if (cal3 == 0) {
    Serial.println("9");
    delay(200);
  }
  else if (cal4 == 0) {
    Serial.println("C");
    delay(200);
  }
   /************************-D******************************/
  digitalWrite(r1, 1);
  digitalWrite(r2, 1);
  digitalWrite(r3, 1);
  digitalWrite(r4, 0);
  cal1 = digitalRead(c1);
  cal2 = digitalRead(c2);
  cal3 = digitalRead(c3);
  cal4 = digitalRead(c4);

  if (cal1 == 0) {
    Serial.println("*");
    delay(200);
  }
  else if (cal2 == 0) {
    Serial.println("0");
    delay(200);
  }

  else if (cal3 == 0) {
    Serial.println("#");
    delay(200);
  }
  else if (cal4 == 0) {
    Serial.println("D");
    delay(200);
  }

}