int buzzer=11;
void setup() {
pinMode(11, OUTPUT);
digitalWrite(11, LOW);
pinMode(10, OUTPUT);
digitalWrite(10, LOW);
pinMode(11, OUTPUT);
digitalWrite(11, LOW);
}

void loop() {
digitalWrite(11, HIGH);
delay(500);
digitalWrite(11, LOW);
delay(500);
digitalWrite(10, HIGH);
delay(500);
digitalWrite(10, LOW);
delay(500);
tone(buzzer, 9);
}