//class counter displaying the count on SSD common anode
int count=0;
int flag=0;
int flag1=0;
void setup() {
  Serial.begin(9600);
  pinMode(12, INPUT);
  pinMode(13, INPUT);
}
void loop() {
  int x =digitalRead(13);
  int y =digitalRead(12);
  if(x==1 && flag==0){
    count++;
      Serial.print("Total Student present: ");
      Serial.println(count); 
   flag=1;
  }
  else if(x==LOW){
    flag=0;
  }
  if(y==1 && flag1==0 && count>0){
    count=count-1;
    if (count<0) count=0;
      Serial.print("Total Student present: ");
      Serial.println(count); 
      flag1==1;
  }
  else if(x==LOW){
    flag1=0;
  }
}