#include <stdio.h>
#include <stdlib.h>
#include <string.h>



int count_pairs_with_sum(int arr[], int n, int target) {
    // TODO: implement this function
    return 0;
}


int main(void) {
    int n;
    if (scanf("%d", &n) != 1) { n = 0; }
    int arr[1000];
    for (int i = 0; i < n; i++) { scanf("%d", &arr[i]); }
    int target;
    if (scanf("%d", &target) != 1) { target = 0; }
    printf("%d\n", count_pairs_with_sum(arr, n, target));
    return 0;
}