import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        System.out.println("请输入数字: ");
        double num1 = scanner.nextDouble();

        System.out.println("请输入操作符 (+, -, *, /, %): ");
        char operator = scanner.next().charAt(0);

        System.out.println("请输入数字: ");
        double num2 = scanner.nextDouble();

        double result = 0;

        switch (operator) {
            case '+':
                result = num1 + num2;
                break;
            case '-':
                result = num1 - num2;
                break;
            case '*':
                result = num1 * num2;
                break;
            case '/':
                if (num2 != 0) {
                    result = num1 / num2;
                } else {
                    System.out.println("错误！除数不能为零。");
                    return;
                }
                break;
            case '%':
                result = num1 % num2;
                break;
            default:
                System.out.println("无效的操作符！");
                return;
        }

        System.out.println("计算结果是: " + result);
    }
}