byte hours = 0;
byte minutes = 0;
byte seconds = 0;

void setup() {
  Serial.begin(9600);

  Serial.print("Enter hours passed: ");
  while (!Serial.available());
  hours = Serial.readString().toInt();
  Serial.println(hours);
  
  Serial.print("Enter minutes passed: ");
  while (!Serial.available());
  minutes = Serial.readString().toInt();
  Serial.println(minutes);
}

void checkTime() {
  seconds++;
  if (seconds >= 60) {
    minutes++;
    seconds = 0;
  }
  if (minutes >= 60) {
    hours++;
    minutes = 0;
  }
  if (hours >= 24) hours = 0;
}

void loop() {
  checkTime();
  delay(1000);

  String time = "Time:- " + String(hours) + ":" + String(minutes) + ":" + String(seconds);
  Serial.println(time);
}