int Trig = 21;
  int Echo = 22;
  int led1 = 18;
  int led2 = 2;
  int led3 = 4;
  int buzzer = 19;

void setup() {
  Serial.begin(9600);
  pinMode(Trig, OUTPUT);
  pinMode(Echo, INPUT);
  pinMode(led1, OUTPUT);
  pinMode(led2, OUTPUT);
  pinMode(led3, OUTPUT);
  pinMode(buzzer, OUTPUT);
}

void loop() {
  digitalWrite(Trig, LOW);
  delayMicroseconds(2);

  digitalWrite(Trig, HIGH);
  delayMicroseconds(10);

  digitalWrite(Trig, LOW);

  long duracao = pulseIn(Echo, HIGH);

  int distancia = (duracao * 0.0343) / 2;

  Serial.println("Distância" + String(distancia));

  if (distancia < 5){
    digitalWrite(led1, LOW);
    digitalWrite(led2, LOW);
    digitalWrite(led3, HIGH);
    tone(buzzer, 1000);
  }else if (distancia < 15){
    digitalWrite(led1, LOW);
    digitalWrite(led2, HIGH);
    digitalWrite(led3, LOW);
    tone(buzzer, 1000, 300);
    noTone(buzzer);
  }else if(distancia < 30){
    digitalWrite(led1, HIGH);
    digitalWrite(led2, LOW);
    digitalWrite(led3, LOW);
    tone(buzzer, 1000, 600);
    noTone(buzzer);
  }else{
     digitalWrite(led1, LOW);
    digitalWrite(led2, LOW);
    digitalWrite(led3, LOW);
    noTone(buzzer);
  }

  delay(500);
}