int contrast=100;
 int  in=12;
 int out=11;
 int led=10;
 int count=0;
 void setup()
 {
  pinMode(12, INPUT);
  pinMode(11, INPUT);
  pinMode(10, OUTPUT);
  Serial.println("visitor counter");
  Serial.print("person in room");
  Serial.begin(9600);

}

void loop() {
  if(digitalRead(in))
  {
    count++;
    Serial.println("person in room");
    Serial.print(count);
    delay(1000);
  }
  if(digitalRead(out))
  {
    count--;
    Serial.println("person in room");
    Serial.print(count);
    delay(1000);

  }
  if(count<=0)
  {
    digitalWrite(10, LOW);
    Serial.println("nobody is in room");
    Serial.print("light is off");
    delay(200);
  }
  else if(count>0)
  {
    digitalWrite(10, HIGH);

  }
  else
  {
    digitalWrite(10, LOW);
  }

 

}