70. UART Buffer

What will be the output on the Serial Monitor when the following code is executed and the user inputs "abc123"?

The setting of the serial monitor is shown below:

void setup() {
Serial.begin(9600);
}
void loop() {
	if (Serial.available() > 0) {
		String input = Serial.readString();
		Serial.print("Input length: ");
		Serial.println(input.length());
	}
}