import java.util.Scanner;
import javax.script.ScriptEngineManager;
import javax.script.ScriptEngine;
import javax.script.ScriptException;
 
public class EvaluateExpression {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
 
        System.out.print("Enter a mathematical expression: ");
        String expression = sc.nextLine();   // Example: 10 + 20 * 3 - 6 / 2
 
        // Create JavaScript engine to evaluate expression
        ScriptEngine engine = new ScriptEngineManager().getEngineByName("JavaScript");
 
        try {
            Object result = engine.eval(expression);
            System.out.println("Result = " + result);
        }
        catch (ScriptException e) {
            System.out.println("Invalid expression!");
        }
 
        sc.close();
    }
}