// Pair Sum

// You have been given an integer array/list(ARR)and a number X.Find and return the total number of pairs in the array/list which sum to X.

// Note:

// Given array/list can contain duplicate elements.

// Input format:

// The first line contains an Integer't'which denotes the number of test cases or queries to be run.Then the test cases follow.

// First line of each test case or query contains an integer'N'representing the size of the first array/list.

// Second line contains'N'single space separated integers representing the elements in the array/list.

// Third line contains an integer'X'.Output format:For each test case,print the total number of pairs present in the array/list.

// Output format:

// For each test case,print the total number of pairs present in the array/list.

// Output for every test case will be printed in a separate line.

// Constraints:

// 1<=t<=10^2

// 0<=N<=10^3

// 0<=X<=10^9

// Time Limit:1 sec

// Sample Input 1:

// 1

// 9

// 1 3 6 2 5 4 3 2 4

// 7

// Sample Output 1:

// 7

// Sample Input 2:

// 2

// 9

// 1 3 6 2 5 4 3 2 4

// 12

// 6

// 2 8 10 5-2 5 10

// Sample Output 2:

// 0

// 2

// Explanation for Input 2:

// Since there doesn'texist any pair with sum equal to 12 for the first query,we print 0.

// For the second query,we have 2 pairs in total that sum up to 10. They are,(2,8)and(5,5).

package Array;

import java.util.Scanner;

public class PairSum {

public static int pairSum(int[] arr, int x) {

int count = 0;

for (int i = 0; i < arr.length; i++) {

for (int j = i + 1; j < arr.length; j++) {

int sum;

sum = arr[i] + arr[j];

if (sum == x) {

count += 1;

}

}

}

return count;

}

public static int[] takingInput() {

Scanner sc = new Scanner(System.in);

int n = sc.nextInt();

int[] arr = new int[n];

for (int i = 0; i < n; i++) {

arr[i] = sc.nextInt();

}

return arr;

}

public static void main(String[] args) {

int[] arr = takingInput();

Scanner sc = new Scanner(System.in);

int x = sc.nextInt();

int n = pairSum(arr, x);

System.out.println(n);

}

}