import java.util.Scanner;

public class Test {

    public static void main(String [] args) { 

         Scanner sc = new Scanner(System.in); 

System.out.println("请输入算法：");

         String go = sc.next();

System.out.println("请输入第一个数：");

         Double a = sc.nextDouble(); 

System.out.println("请输入第二个数：");

         Double b =  sc.nextDouble();

if(go.equals("+")){

    Double sum = a+b;

    System.out.println("他们的和为"+sum);

}

if(go.equals("-")){

     Double sum = a-b;

    System.out.println("他们的差为"+sum);

}

if(go.equals("*")){

     Double sum = a*b;

    System.out.println("他们的积为"+sum);

}

if(go.equals("/")){

    Double sum = a/b;

    System.out.println("他们的商为"+sum);

}

}

}