#include <LiquidCrystal.h>
int rs=12,en=11,D4=5,D5=4,D6=3,D7=2;
LiquidCrystal lcd(rs, en, D4, D5, D6, D7);
String n1,n2;
int res;

void setup() {
  lcd.begin(16, 2);
  // you can now interact with the LCD, e.g.:
  Serial.begin(9600);
  //Serial.print("Hello World!");
}

void loop() {
lcd.clear();
lcd.setCursor(0,0);
lcd.print("Input number 1");
while(Serial.available()==0){}
n1=Serial.readString();
lcd.setCursor(0,1);
lcd.print(n1);
delay(1000);

lcd.clear();
lcd.setCursor(0,0);
lcd.print("Input number 2");
while(Serial.available()==0){}
n2=Serial.readString();
lcd.setCursor(0,1);
lcd.print(n2);
delay(1000);

lcd.clear();
lcd.setCursor(0,0);
lcd.print("Addition is:");
lcd.setCursor(0,1);
res=n1.toInt()+n2.toInt();
lcd.print(res);
delay(500);
}