#define trig 13
#define echo 12

void setup() {
  Serial.begin(115200);
  pinMode(trig, OUTPUT);
  pinMode(echo, INPUT);
  pinMode(10, OUTPUT);
  pinMode(9, OUTPUT);
  pinMode(8, OUTPUT);
}

void loop() {
  digitalWrite(trig, HIGH);
  delayMicroseconds(10);
  digitalWrite(trig, LOW);

  int pulse = pulseIn(echo,HIGH);
  int distance = pulse/58;

  Serial.print(distance);
  Serial.println(" CM");

  if (distance > 100){
    digitalWrite(10, HIGH);
  }
  else if (distance < 250){
    digitalWrite(10, LOW);
  }
  if (distance > 250){
    digitalWrite(9, HIGH);
  }
  else if (distance < 250){
    digitalWrite(9, LOW);
  }
  if (distance > 400){
    digitalWrite(8, HIGH);
  }
  else if (distance < 400){
    digitalWrite(8, LOW);
  }
}