#include <LiquidCrystal.h>
int rs = 7;
int en = 8 ;
int d4 = 9 ;
int d5 = 10 ;
int d6 = 11 ;
int d7 = 12 ;
LiquidCrystal lcd(rs,en,d4,d5,d6,d7);
String msg1 = "Enter 1st number" ;
String msg3 = "Input (+,-,*,/)" ;
String msg2 = "Enter 2nd number" ;
double num1 ;
double num2 ;
String op ;
int dt = 500 ;
double ans ;
void setup() {
  // put your setup code here, to run once:
  lcd.begin(16,2);
  Serial.begin(9600);
}

void loop() {
  // put your main code here, to run repeatedly:
  lcd.setCursor(0,0);
  lcd.print(msg1);
  while(Serial.available()==0){}
  num1 = Serial.parseFloat();
  delay(dt);

  lcd.clear();
  lcd.setCursor(0,0);
  lcd.print(msg2);
  while(Serial.available()==0){}
  num2 = Serial.parseFloat();
  delay(dt);

  lcd.clear();
  lcd.setCursor(0,0);
  lcd.print(msg3);
  while(Serial.available()==0){}
  op = Serial.readString();
  delay(dt);

  if(op == "+"){
    ans = (num1+num2);
  }
  if(op == "-"){
    ans = (num1-num2);
  }
  if(op == "*"){
    ans = (num1*num2);
  }
  if(op == "/"){
    ans = (num1/num2);
  }
  lcd.clear();
  lcd.setCursor(0,0);
  lcd.print("The answer is :");
  delay(dt);
  lcd.setCursor(0,1);
  lcd.print(ans);
}