#define TRIGGER 3
#define ECHO 2
int cm_cal;
int led=9;
void setup() {
  Serial.begin(9600);
  pinMode(TRIGGER, OUTPUT);
  pinMode(ECHO, INPUT);
  pinMode(led,OUTPUT);
}
void loop() {
  digitalWrite(TRIGGER, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIGGER, LOW);
  int duration = pulseIn(ECHO, HIGH);
  cm_cal=duration/58;
  Serial.println(cm_cal);
  delay(1000);
  if(cm_cal<100 && cm_cal>=50)
  {
    digitalWrite(led, HIGH);
    delay(100);
    digitalWrite(led, LOW);
    delay(1000);
    Serial.println("1");
  }
  if(cm_cal<50 && cm_cal>=20)
  {
    digitalWrite(led, HIGH);
    delay(100);
    digitalWrite(led, LOW);
    delay(500);
    Serial.println("0");
  }
  if(cm_cal<10)
  {
    digitalWrite(led, HIGH);
    delay(100);
    digitalWrite(led, LOW);
    delay(100);
    Serial.println("3");
  }
}