NA錯誤:
您的答案為: Two same roots x=-4
正確答案為: Two same roots x=-1

package test;
import java.util.Scanner;
public class test {
 public static void main(String[]args){
 Scanner sc=new Scanner(System.in);
 while(sc.hasNext()){
 double a=sc.nextDouble();
 double b=sc.nextDouble();
 double c=sc.nextDouble();
 double num1=(-b)/2*a;
 double num2=Math.sqrt(b*b-4*a*c)/2*a;
 double total=b*b-4*a*c;
 int x1=(int)(num1+num2);
 int x2=(int)(num1-num2);
 if(total>0){
 System.out.println("Two different roots x1="+x1+" , x2="+x2);}
 else if(total==0){
 System.out.println("Two same roots x="+x1);}
 else {System.out.println("No real root");}
 }}}


但我自己跑都沒錯，也沒出現NA的錯誤，有人可以幫我解一下嗎