#include <stdio.h> #include <stdlib.h> int cmp_int (const void *ap, const void *bp) { int a = *(int *)ap; int b = *(int *)bp; if (a < b) { return -1; } if (a > b) { return 1; } return 0; } int main () { int n = 0; int m = 0; int a[300000] = {}; int res = 0; long long ans = 0LL; int idx = 0; res = scanf("%d", &n); res = scanf("%d", &m); for (int i = 0; i < n; i++) { res = scanf("%d", a+i); } if (m%2 == 1) { printf("0\n"); return 0; } qsort(a, n, sizeof(int), cmp_int); for (int i = 0; i < n; i++) { while (idx < n && a[idx] < a[i]+m/2) { idx++; } if (idx < n && a[idx] == a[i]+m/2) { ans += 1LL; } } ans *= (long long)(n-2); printf("%lld\n", ans); return 0; }