#include <LiquidCrystal_I2C.h>
LiquidCrystal_I2C lcd(0x27,  16, 2); 


void setup(){
  lcd.init();
  lcd.backlight();
}

void loop(){
  String words = "students of 150-21 group";
  for(int led = 15; led >= 0; led--){
    lcd.clear();
    lcd.setCursor(led, 0);
    lcd.print(words);
    delay(200);

    if(led == 0){
      for(int i = words.length(); i >= 0; i--){
        lcd.clear();
        words = words.substring(1, i);
        lcd.print(words);
        delay(200);
      }
    }
  }
}