int uz = 12;
long dl;
long cm;

long microsecondsToCentimeters(long microseconds) {
  return microseconds / 29 / 2;
}

void setup() {
  // put your setup code here, to run once:
  Serial.begin(9600);
}

void loop() {
  // put your main code here, to run repeatedly:
  pinMode(uz, OUTPUT);
  digitalWrite(uz, HIGH);

  pinMode(uz, INPUT);
  dl = pulseIn(uz, HIGH);

  cm = microsecondsToCentimeters(dl);

  Serial.print(cm);
  Serial.println("cm");
  Serial.println();
  delay(100);
}