int ir=3;
int led=11;
void setup() {
  // put your setup code here, to run once:
  pinMode(ir, INPUT);
  pinMode(led, OUTPUT);
  Serial.begin(9600);
}

void loop() {
  // put your main code here, to run repeatedly:
  int sensedata=digitalRead(ir);
  Serial.print("Sensor value: ");
  Serial.println(sensedata);
  if (sensedata==0)  {
    digitalWrite(led, HIGH);
  }
  else {
    digitalWrite(led, LOW);
  }
}