#include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #define all(x) (x).begin(),(x).end() #define rep(i,m,n) for(int i = m;i < n;++i) #define pb push_back #define rrep(i,m,n) for(int i = m;i >= n;--i) #define INF INT_MAX-1; using namespace std; using ll = long long; using R = double; const ll inf = 1LL << 50; const ll MOD = 1e9 + 7; struct edge { ll from; ll to; ll cost; }; int main(){ ll n, x; cin >> n >> x; vectora(n); rep(i, 0, n)cin >> a[i]; sort(all(a)); ll ans = 0; rep(i, 0, n) { ll temp1, temp2; if (x - a[i] > a[n - 1]) { continue; } else if (x-a[i]==a[n-1]) { //x-a[i]以下の個数 temp1 = n; //x-a[i]未満の個数 temp2 = lower_bound(all(a), x - a[i]) - a.begin(); } else { //x-a[i]以下の個数 temp1 = upper_bound(all(a), x - a[i]) - a.begin(); //x-a[i]未満の個数 temp2 = lower_bound(all(a), x - a[i]) - a.begin(); } ans += temp1 - temp2; } cout << ans << endl; return 0; }