Arduino sketch to ask for how many seconds to delay, for my spouse-safe wrist alarm, first working version, don't expect beauty

delay-prompt

int powerPin = 17;
int groundPin = 19;
int failcount = 0;
char buffer[18];

void setup() {
  Serial.begin(9600);
  Serial.flush();
  pinMode(powerPin,OUTPUT);
  pinMode(groundPin,OUTPUT);
};

void loop() { 
  if (Serial.available() > 0) {
    int index=0;
    delay(100); // let the buffer fill up
    int numChar = Serial.available();
    if (numChar>15) {
      numChar=15;
    }
    while (numChar--) {
      buffer[index++] = Serial.read();
    }
    splitString(buffer);
  } else { // no input, snooze for five minutes
    failcount++;
    delay(1000); // wait one second
    if (failcount > 30) { // after thirty seconds looking for serial input once per second
      // start the five minute delay
      delay(1000 * 60 * 5);
      while(1){
        buzz();
      }
    }
  }
}
void splitString(char* data) {
  Serial.print("Data entered: ");
  Serial.println(data);
  unsigned long Ans = strtol(data, NULL, 10);
  Ans = constrain(Ans,0,30000);
  Serial.print("Delaying ");
  Serial.print(Ans);
  Serial.println(" seconds.");
  Serial.print("going to delay milliseconds: ");
  Ans = Ans * 1000;
  Serial.println(Ans);
  delay(Ans);
  while(1){
    buzz();
  }
  // Clear the text and serial buffers
  for (int x=0; x<16; x++) {
    buffer[x]='\0';
  }
  Serial.flush();
}

void buzz() {
  int amount = 500;
  delay(amount);
  digitalWrite(powerPin,HIGH);
  delay(amount);
  digitalWrite(powerPin,LOW);
}