int trigger=12;
int echo=14;
float distance;

void setup() {
Serial.begin(115200);
pinMode(trigger, OUTPUT);
pinMode(echo, INPUT);
pinMode(23, OUTPUT);
pinMode(22, OUTPUT);
pinMode(21, OUTPUT);

}

int kavin(){
digitalWrite(trigger, LOW);
delay(10);
digitalWrite(trigger, HIGH);
delay(100);
digitalWrite(trigger,LOW);
distance=pulseIn(echo, HIGH);
return(distance*0.034/2)+1;

}
void loop() {
 int actual_distance= kavin();
 Serial.println(actual_distance);
  delay(10); 
  if(actual_distance>300){
    digitalWrite(21, HIGH);
    digitalWrite(22, LOW);
    digitalWrite(23, LOW);
  }
else if(actual_distance>=200 && actual_distance<=300){
  digitalWrite(22, HIGH);
  digitalWrite(21, LOW);
  digitalWrite(23, LOW);
}
else if(actual_distance>=0 && actual_distance<200){
  digitalWrite(23, HIGH);
  digitalWrite(22, LOW);
  digitalWrite(21, LOW);

}
else{
  digitalWrite(23, LOW);
  digitalWrite(22, LOW);
  digitalWrite(21, LOW);
  delay(10);
}
}