相反数

package geekfly.test;

import java.util.Scanner;

public class 相反数 {

    public static void main(String[] args) {
        int total = 0,all=0,arr1[]=new int[5000],arr2[]=new int[5000];
        Scanner sc = new Scanner(System.in);
        all = Integer.parseInt(sc.nextLine());
        int num = 0,x=0,y=0;
        for(int i=0;i<all;i++){
            num = sc.nextInt();
            if(num>=0){
                arr1[x] = num;
                x++;
            }
            else{
                arr2[y] = num;
                y++;
            }
        }
        for(int i=0;i<x;i++){
            int nn = arr1[i];
            for(int j=0;j<y;j++){
                if(nn==-arr2[j]){
                    total++;
                    break;
                }
            }
        }
System.out.println(total);
    }

}