//#pragma GCC optimize("Ofast") //#pragma GCC target("avx") //#undef LOCAL #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include using namespace std; using uint = unsigned int; using ll = long long; using ull = unsigned long long; constexpr ll TEN(int n) { return (n == 0) ? 1 : 10 * TEN(n - 1); } template using V = vector; template using VV = V>; #include struct Scanner { int fd = -1; char line[(1 << 15) + 1]; size_t st = 0, ed = 0; void reread() { memmove(line, line + st, ed - st); ed -= st; st = 0; ed += ::read(fd, line + ed, (1 << 15) - ed); line[ed] = '\0'; } bool succ() { while (true) { if (st == ed) { reread(); if (st == ed) return false; } while (st != ed && isspace(line[st])) st++; if (st != ed) break; } if (ed - st <= 50) { bool sep = false; for (size_t i = st; i < ed; i++) { if (isspace(line[i])) { sep = true; break; } } if (!sep) reread(); } return true; } template ::value, int> = 0> bool read_single(T& ref) { if (!succ()) return false; while (true) { size_t sz = 0; while (st + sz < ed && !isspace(line[st + sz])) sz++; ref.append(line + st, sz); st += sz; if (!sz || st != ed) break; reread(); } return true; } template ::value, int> = 0> bool read_single(T& ref) { if (!succ()) return false; bool neg = false; if (line[st] == '-') { neg = true; st++; } ref = T(0); while (isdigit(line[st])) { ref = 10 * ref + (line[st++] & 0xf); } if (neg) ref = -ref; return true; } template bool read_single(V& ref) { for (auto& d : ref) { if (!read_single(d)) return false; } return true; } void read() {} template void read(H& h, T&... t) { bool f = read_single(h); assert(f); read(t...); } Scanner(FILE* fp) : fd(fileno(fp)) {} }; struct Printer { public: template void write() {} template void write(const H& h, const T&... t) { if (F) write_single(' '); write_single(h); write(t...); } template void writeln(const T&... t) { write(t...); write_single('\n'); } Printer(FILE* _fp) : fp(_fp) {} ~Printer() { flush(); } private: static constexpr size_t SIZE = 1 << 15; FILE* fp; char line[SIZE], small[50]; size_t pos = 0; void flush() { fwrite(line, 1, pos, fp); pos = 0; } void write_single(const char& val) { if (pos == SIZE) flush(); line[pos++] = val; } template ::value, int> = 0> void write_single(T val) { if (pos > (1 << 15) - 50) flush(); if (val == 0) { write_single('0'); return; } if (val < 0) { write_single('-'); val = -val; // todo min } size_t len = 0; while (val) { small[len++] = char(0x30 | (val % 10)); val /= 10; } for (size_t i = 0; i < len; i++) { line[pos + i] = small[len - 1 - i]; } pos += len; } void write_single(const string& s) { for (char c : s) write_single(c); } void write_single(const char* s) { size_t len = strlen(s); for (size_t i = 0; i < len; i++) write_single(s[i]); } template void write_single(const V& val) { auto n = val.size(); for (size_t i = 0; i < n; i++) { if (i) write_single(' '); write_single(val[i]); } } }; template struct SimpleSeg { D e; Op op; int n, sz, lg; // size(extended to 2^i), lg V d; SimpleSeg(const V& v, D _e, Op _op) : e(_e), op(_op) { n = int(v.size()); lg = 1; while ((1 << lg) < n) lg++; sz = 1 << lg; d = V(2 * sz, e); for (int i = 0; i < n; i++) d[sz + i] = v[i]; for (int i = sz - 1; i >= 0; i--) { update(i); } } void update(int k) { d[k] = op(d[2 * k], d[2 * k + 1]); } void set(int p, D x) { assert(0 <= p && p < n); p += sz; d[p] = x; for (int i = 1; i <= lg; i++) update(p >> i); } D single(int p) const { assert(0 <= p && p < n); return d[p + sz]; } D sum(int a, int b) const { assert(a <= b); D sml = e, smr = e; a += sz; b += sz; while (a < b) { if (a & 1) sml = op(sml, d[a++]); if (b & 1) smr = op(d[--b], smr); a >>= 1; b >>= 1; } return op(sml, smr); } D all_sum() const { return d[1]; } // min i s.t. f(d[a] + d[a+1] + ... d[i]) == true (or return n + 1) template int search_left(int a, Comp f) { a += sz; D sm = e; if (f(e)) return a; while (true) { if (f(op(sm, d[a]))) { while (a < sz) { a *= 2; if (!f(op(sm, d[a]))) { sm = op(sm, d[a]); a++; } } a = a + 1 - sz; return a; } if (a & 1) { sm = op(sm, d[a]); a++; if ((a & -a) == a) break; } a >>= 1; } return n + 1; } }; template SimpleSeg get_simple_seg(V v, D e, Op op) { return SimpleSeg(v, e, op); } template struct SegTree { D e_d; L e_l; OpDD op_dd; OpDL op_dl; OpLL op_ll; int sz, lg; //(2^lgに拡張後の)サイズ, lg V d; V lz; SegTree(const V& v, D _e_d, L _e_l, OpDD _op_dd, OpDL _op_dl, OpLL _op_ll) : e_d(_e_d), e_l(_e_l), op_dd(_op_dd), op_dl(_op_dl), op_ll(_op_ll) { int n = int(v.size()); lg = 1; while ((1 << lg) < n) lg++; sz = 1 << lg; d = V(2 * sz, e_d); lz = V(2 * sz, e_l); for (int i = 0; i < n; i++) d[sz + i] = v[i]; for (int i = sz - 1; i >= 0; i--) { update(i); } } void all_add(int k, L x) { d[k] = op_dl(d[k], x); lz[k] = op_ll(lz[k], x); } void push(int k) { all_add(2 * k, lz[k]); all_add(2 * k + 1, lz[k]); lz[k] = e_l; } void update(int k) { d[k] = op_dd(d[2 * k], d[2 * k + 1]); } void set(int p, D x) { p += sz; for (int i = lg; i >= 1; i--) push(p >> i); d[p] = x; for (int i = 1; i <= lg; i++) update(p >> i); } void add(int a, int b, L x, int l, int r, int k) { if (b <= l || r <= a) return; if (a <= l && r <= b) { all_add(k, x); return; } push(k); int mid = (l + r) / 2; add(a, b, x, l, mid, 2 * k); add(a, b, x, mid, r, 2 * k + 1); update(k); } void add(int a, int b, L x) { add(a, b, x, 0, sz, 1); } D single(int p) { p += sz; for (int i = lg; i >= 1; i--) push(p >> i); return d[p]; } D sum(int a, int b, int l, int r, int k) { if (b <= l || r <= a) return e_d; if (a <= l && r <= b) return d[k]; push(k); int mid = (l + r) / 2; return op_dd(sum(a, b, l, mid, 2 * k), sum(a, b, mid, r, 2 * k + 1)); } D sum(int a, int b) { return sum(a, b, 0, sz, 1); } D all_sum() const { return d[1]; } }; template SegTree get_seg(V v, D e_d, L e_l, OpDD op_dd, OpDL op_dl, OpLL op_ll) { return SegTree(v, e_d, e_l, op_dd, op_dl, op_ll); } Scanner sc = Scanner(stdin); Printer pr = Printer(stdout); int main() { int n; ll val; sc.read(n, val); V a(n); for (int i = 0; i < n; i++) { sc.read(a[i]); } auto av = a; sort(av.begin(), av.end()); av.erase(unique(av.begin(), av.end()), av.end()); auto get_i = [&](ll x) { auto it = lower_bound(av.begin(), av.end(), x); if (it == av.end() || *it != x) return -1; return int(it - av.begin()); }; int L = int(av.size()); using P = pair; VV

sums(L, {P(-1, 0)}); // (idx, sum_idx) { V bpos(L, 0); for (int i = 0; i < n; i++) { int idx = get_i(a[i]); ll bk = sums[idx].back().second; sums[idx].push_back(P(i, bk + bpos[idx])); bpos[idx] = i; } for (int idx = 0; idx < L; idx++) { ll bk = sums[idx].back().second; sums[idx].push_back(P(n, bk + bpos[idx])); } } V

ap(n); for (int i = 0; i < n; i++) { ap[i] = P(a[i], i); } auto seg = get_simple_seg(ap, P(TEN(10), -1), [&](P a, P b) { return min(a, b); }); ll sum = 0; auto single = [&](int l, int mid, int r) { if (r - mid < mid - l) { for (int i = mid; i < r; i++) { int yi = get_i(val - a[i]); if (yi == -1) continue; int i1 = int(lower_bound(sums[yi].begin(), sums[yi].end(), P(l, -1)) - sums[yi].begin()); int i2 = int(lower_bound(sums[yi].begin(), sums[yi].end(), P(mid + 1, -1)) - sums[yi].begin()); ll c0 = i2 - i1; ll c1 = sums[yi][i2].second - sums[yi][i1].second; sum += c0 * (i + 1) - c1; } } else { for (int i = l; i <= mid; i++) { int yi = get_i(val - a[i]); if (yi == -1) continue; int i1 = int(lower_bound(sums[yi].begin(), sums[yi].end(), P(mid, -1)) - sums[yi].begin()); int i2 = int(lower_bound(sums[yi].begin(), sums[yi].end(), P(r, -1)) - sums[yi].begin()); ll c0 = i2 - i1; ll c1 = sums[yi][i2].second - sums[yi][i1].second; sum += c1 - c0 * (i - 1); } } }; auto dfs = [&](auto self, int l, int r) { if (l == r) return; if (l + 1 == r) { if (2 * a[l] == val) { sum++; } return; } ll lw = seg.sum(l, r).first; V lws = {l - 1}; { int p = l; while (p < r) { auto x = seg.sum(p, r); if (x.first != lw) break; lws.push_back(int(x.second)); p = int(x.second + 1); } } lws.push_back(r); int num = int(lws.size()); for (int i = 1; i < num - 1; i++) { single(lws[i - 1] + 1, lws[i], lws[i + 1]); } for (int i = 0; i < num - 1; i++) { self(self, lws[i] + 1, lws[i + 1]); } }; dfs(dfs, 0, n); pr.writeln(sum); return 0; }