#define _USE_MATH_DEFINES #define _CRT_SECURE_NO_WARNINGS #include using namespace std; /*BigInteger #include #include #include namespace xxx = boost::multiprecision; using Bint = xxx::cpp_int; using Real = xxx::number>; */ #define int long long #define pb(x) push_back(x) #define m0(x) memset((x), 0LL, sizeof(x)) #define mm(x) memset((x), -1LL, sizeof(x)) //container #define ALL(x) (x).begin(), (x).end() #define RALL(a) (a).rbegin(), (a).rend() #define EACH(i, c) for (typeof((c).begin()) i = (c).begin(); i != (c).end(); ++i) #define EXIST(s, e) ((s).find(e) != (s).end()) #define UNIQUE(v) (v).erase(unique((v).begin(), (v).end()), (v).end()); #define PERM(c) \ sort(ALL(c)); \ for (bool c##p = 1; c##p; c##p = next_permutation(ALL(c))) // debug #define GET_VAR_NAME(variable) #variable #define test(x) cout << GET_VAR_NAME(x) << " = " << x << endl; // bit_macro #define Bit(n) (1LL << (n)) #define Bitset(a, b) (a) |= (1LL << (b)) #define Bitunset(a, b) (a) &= ~(1LL << (b)) #define Bitcheck(a, b) ((((a) >> (b)) & 1LL) == 1LL) #define Bitcount(a) __builtin_popcountll((a)) //typedef typedef long long lint; typedef unsigned long long ull; typedef complex Complex; typedef pair P; typedef tuple TP; typedef vector vec; typedef vector mat; //constant constexpr int INF = (int)1e18; constexpr int MOD = (int)1e9 + 7; constexpr double PI = (double)acos(-1); constexpr double EPS = (double)1e-10; constexpr int dx[] = {-1, 0, 0, 1, 0, -1, -1, 1, 1}; constexpr int dy[] = {0, -1, 1, 0, 0, 1, -1, 1, -1}; // template void chmax(T &a, T b) { a = max(a, b); } template void chmin(T &a, T b) { a = min(a, b); } // inline int toInt(string s) { int v; istringstream sin(s); sin >> v; return v; } template inline string toString(T x) { ostringstream sout; sout << x; return sout.str(); } // struct Accelerate_Cin { Accelerate_Cin() { cin.tie(0); ios::sync_with_stdio(0); cout << fixed << setprecision(20); }; }; int N, X; vec a; signed main() { cin >> N >> X; a.resize(N); for (int i = 0; i < N; i++) cin >> a[i]; sort(ALL(a)); int ans = 0; for (int i = 0; i < N; i++) { ans += upper_bound(ALL(a), X - a[i]) - lower_bound(ALL(a), X - a[i]); } cout << ans << endl; return 0; }