int trigger=4;
int echo=5;
int rled=12, yled=14, gled=27;

void setup() {
  // put your setup code here, to run once:
  Serial.begin(115200);
  pinMode(trigger, OUTPUT);
  pinMode(echo, INPUT);
  pinMode(rled, OUTPUT);
  pinMode(yled, OUTPUT);
  pinMode(gled, OUTPUT);
}

int finding_distance(){
  digitalWrite(trigger, HIGH);
  delay(100);
  digitalWrite(trigger, LOW);
  float a=pulseIn(echo, HIGH);
  return(a*0.034/2);
}

void loop() {
  int d=finding_distance();
  if(d>300) {
    Serial.println("YOU ARE SAFE");
    digitalWrite(gled, HIGH);
    digitalWrite(yled, LOW);
    digitalWrite(rled, LOW);
  } else if(d<300 && d>=200) {
      Serial.println("YOU ARE UNSAFE");
      digitalWrite(yled, HIGH);
      digitalWrite(rled, LOW);
      digitalWrite(gled, LOW);
    } else {
      Serial.println("YOU ARE IN DANGER");
      digitalWrite(rled, HIGH);
      digitalWrite(yled, LOW);
      digitalWrite(gled, LOW);
      }
  Serial.println(d);
}