int op = A0;
int hp = 0;
void setup() 
{
  pinMode(op, INPUT);
  Serial.begin(9600);
}
void loop()
{
  hp = analogRead(op);
  if(hp > 512)  // Threshold value (adjust as per your sensor/input)
  {
    Serial.println("stop something is ahead!");
  }
  else
  {
    Serial.println("path is clear");
  }
  delay(2000);
}