CCF系列之相反数(201403-1)

 1 package ccf_test2014_03;
 2 
 3 import java.util.Scanner;
 4 
 5 public class Opposite {
 6     
 7     final static int MAX = 1000;
 8 
 9     public static void main(String[] args) {
10         
11         int[] shuju = new int[MAX];
12         
13           Scanner input = new Scanner(System.in);
14           
15           int n = input.nextInt();
16           
17           input.nextLine();
18           
19           int result = 0;
20           
21           for(int i = 0; i < n; i++){
22               
23               int num = input.nextInt();
24               
25               num = Math.abs(num);
26               
27               shuju[num]++;
28               
29               if(shuju[num]>1){
30                   
31                   result++;
32               }    
33           }
34          System.out.println(result);
35     }
36 }