#include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include using namespace std; using i64 = int64_t; using i32 = int32_t; template void init_n(vector& v, size_t n, U x) { v = vector(n, x); } template void init_n(vector& v, size_t n) { init_n(v, n, T()); } template void read_n(vector& v, size_t n, size_t o = 0) { v = vector(n+o); for (size_t i=o; i> v[i]; } template void read_n(T a[], size_t n, size_t o = 0) { for (size_t i=o; i> a[i]; } template T gabs(const T& x) { return max(x, -x); } #define abs gabs i64 n, x, c[100001]; int main() { cin >> n >> x; for (i64 i = 0; i < n; ++i) { i64 y; cin >> y; c[y]++; } i64 ans = 0; for (i64 i = 0; i <= 100000; ++i) { i64 j = x - i; if (0 <= j && j <= 100000) { ans += c[i] * c[j]; } } cout << ans << '\n'; return 0; }