Passenger Detection In Vehicles Door

#include <LiquidCrystal.h>
int in = 15;
int inpr = 16;
int out = 14;
int outpr = 17;
int ppl = 0;
LiquidCrystal lcd(12, 11, 5, 4, 3, 2);
bool pi = 0;
bool po = 0;
void setup() {
pinMode(15, INPUT);
pinMode(14, INPUT);
pinMode(16, OUTPUT);
pinMode(17, OUTPUT);
  lcd.begin(16,2);
}
void loop() {
  lcd.clear();
  digitalWrite(outpr, HIGH);
  digitalWrite(inpr, HIGH);
  pi = digitalRead(in);
  po = digitalRead(out);
  if (pi ==1){
  ppl--;
    delay(500);
  }
  else if (po ==1) {
  ppl++;
    delay(500);
  }
  ppl = constrain(ppl,0,50);
  lcd.setCursor(0,0);
  lcd.print("Passenger");
  lcd.setCursor(11,0);
  lcd.print(ppl);
  if (ppl>=20) {
  lcd.setCursor(0,1);
  lcd.print ("Please Wait");
  delay(1000);          
  }
  if (ppl<=19) {
   lcd.setCursor(0,1);
   lcd.print("Total In");
   delay(1000);
   }
}