int trigpin = 3;
int echopin = 2;

int time;
float dec;

void setup() {
  // put your setup code here, to run once:
  pinMode(trigpin, OUTPUT);
  pinMode(echopin, INPUT);

  Serial.begin(9600);
}

void loop() {
  // put your main code here, to run repeatedly:
  digitalWrite(trigpin, LOW);
  delayMicroseconds(2);

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

  digitalWrite(trigpin, LOW);

  time = pulseIn(echopin, HIGH);
  dec = 0.034 * time * 0.5;

  Serial.println("time: " + String(time / 1000.));
  Serial.println("dectnce: " + String(dec));

  delay(500);

}