#include <LiquidCrystal.h>

const int rs = 26;
const int en = 25;
const int D4 = 13;
const int D5 = 12;
const int D6 = 14;
const int D7 = 27;
int dt = 3000;

// Create an LCD Object. Parameters: (rs,enable,D4,D5,D6,D7)

LiquidCrystal lcd(rs,en,D4,D5,D6,D7);
float firstNum;
float secNum;
float answer;
String op;

void setup()
{
  // set up the LCD's number of columns and rows
  lcd.begin(16,2);
  // Clears the Screen
  lcd.clear();
  Serial.begin(115200);
}

void loop()
{
  lcd.setCursor(0,0);
  // Print the message
  lcd.print("Input 1st Number");
  Serial.println(" Input 1st Number ");
  while(Serial.available() == 0)
  {
  }
  firstNum = Serial.parseFloat();
  lcd.clear();

  lcd.setCursor(0,0);
  lcd.print("Input 2nd Number");
  Serial.println(" Input 2nd Number ");
  while(Serial.available() == 0)
  {
  }
  secNum = Serial.parseFloat();
  lcd.clear();
  lcd.setCursor(0,0);
  lcd.print("Input(+,_,*,/)");
  Serial.println("Input(+,_,*,/)");
  while(Serial.available() == 0)
  {
  }
  op = Serial.readString();
  if(op == "+")
  {
    answer = firstNum + secNum;
  }else if(op == "-")
  {
    answer = firstNum - secNum;
  }else if(op == "*")
  {
    answer = firstNum * secNum;
  }else if(op == "/")
  {
    answer = firstNum / secNum;
  }
  lcd.clear();
  lcd.setCursor(0,0);
  lcd.print(firstNum);
  Serial.println(firstNum);
  lcd.print(op);
  Serial.println(op);
  lcd.print(secNum);
  Serial.println(secNum);
  lcd.print("=");
  Serial.println("=");
  lcd.print(answer);
  Serial.println(answer);
  lcd.setCursor(0,1);
  lcd.print("Thank You");
  Serial.println("Thank You");
  delay(dt);
  lcd.clear();
}