int counter = 0;          // Initialize a counter variable
int increment = 1;        // Initialize the increment variable

void setup() {
  Serial.begin(9600);     // Start serial communication at 9600 baud
}

void loop() {
  Serial.println(counter);  // Print the current value of the counter

  counter = counter + increment;  // Increment the counter

  // Reverse the increment direction when limits are reached
  if (counter >= 10 || counter <= 0) {
    increment = -increment;  // Change the direction of increment
  }

  delay(500);  // Wait for 500 milliseconds
}