int led=18;
int ir=23;

int val=0;

void setup(){

Serial.begin(9600);
  pinMode(ir,INPUT);
  pinMode(led,OUTPUT);
}

void loop(){

val=digitalRead(ir);
if(val==HIGH){
  digitalWrite(led,HIGH);
  delay(200);
  Serial.println("someone is ahead");
}
else{
  digitalWrite(led,LOW);
  delay(200);
  Serial.println("All clear now you can go");
}
}