#include <LiquidCrystal_I2C.h>
LiquidCrystal_I2C lcd(0x27,16,2); //create object of lcd
#include <HCSR04.h>
UltraSonicDistanceSensor hc(4, 3);
void setup() {
  // put your setup code here, to run once:
  lcd.init();
  lcd.backlight();

}

void loop() {
  // put your main code here, to run repeatedly:
  if (hc.measureDistanceCm() > 100 || hc.measureDistanceCm() >= 400) {
    lcd.println("...");
    Serial.println("...");
  }
  else if (hc.measureDistanceCm() >= 50) {
    lcd.print("Who's there?");
    Serial.println("Who's there?");
  }
  else if (hc.measureDistanceCm() < 20) {
    lcd.print("how can i help you?");
    Serial.println("how can i help you?");
  }
  delay(100);
}