素數對

題目描述：

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class HW03 {
    public static void main(String[] args)throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        int target = Integer.parseInt(br.readLine());
        int[] numbers = new int[target];
        int count = 0;
        int result = 0;
        for(int i =2; i <= target; i++){
            int judge = 0;
            for(int j = 2; j < i;j++){
                // 判斷是否為質素
                if(i % j == 0){
                    judge = 1;
                    break;
                }
            }
            if(judge == 0){
                numbers[count] = i;
                count++;
            }
        }
        for(int i = 0; i<count - 1; i++){
            for(int j = i; j < count; j++){
                if(numbers[i] + numbers[j] == target){
                    result++;
                    break;
                }
            }
        }
        System.out.println(result);

    }
}