const char codice[5] = {'1', 'a', '+', '$', '3'};
char seq[5];

void setup() {
  // put your setup code here, to run once:
  Serial. begin (115200);
  seq[0] = '1';
  seq[1] = 'a';
  seq[2] = '+';
  seq[3] = '$';
  seq[4] = '3';
}

void loop() {
  // put your main code here, to run repeatedly:
  bool ok = true;
  for (int i = 0; i < 5; i++)
  {
    if (seq[i] != codice[i])
    {
      ok = false;
      break;
    }
  }
  
  if(ok)
  {
    Serial.println("Sequenza corretta");
  }
  else
  {
    Serial.println("Sequenza errata");
  }
  
  delay (500);
}