import java.util.Scanner;

public class SimpleCalculator {

public static void main(String[] args) {

Scanner sc=new Scanner(System.in);

System.out.println("---JAVA CALCULATOR---");

boolean flag= true;

while(flag){

System.out.print("Start/Exit: ");

String calculator= sc.next();

if(calculator.equals("start") || calculator.equals("Start")){

System.out.print("Calculate: ");

double n1= sc.nextInt();

char op= sc.next().charAt(0);

double n2= sc.nextInt();

double result;

if(op=='+' || op=='-' || op=='*' || op=='/'){

if(op=='+'){

result= n1 + n2;

}

else if(op=='-'){

result= n1-n2;

}

else if(op=='*'){

result=n1*n2;

}

else{

result= n1/n2;

}

System.out.println(result);

}

else{

System.out.println("Invalid operation");

}

}

else if(calculator.equals("exit")){

flag= false;

}

}

}

}