/** * @FileName a.cpp * @Author kanpurin * @Created 2020.10.20 15:56:17 **/ #include "bits/stdc++.h" using namespace std; typedef long long ll; template < class Monoid > struct SegmentTree { private: using Func = std::function< Monoid(Monoid, Monoid) >; Func F; Monoid UNITY; int n; std::vector< Monoid > node; int _binary_search(int a, int b, const std::function &f, Monoid &s, int k = 0, int l = 0, int r = -1) { if (r < 0) r = n; if (r <= a || b <= l) return n; if (a <= l && r <= b && !f(F(s,node[k]))) { s = F(s,node[k]); return n; } if (l == r - 1) {s = F(s,node[k]); return l;} int ret = _binary_search(a, b, f, s, 2 * k + 1, l, (r - l) / 2 + l); return ret != n ? ret : _binary_search(a, b, f, s, 2 * k + 2, (r - l) / 2 + l, r); } public: SegmentTree() {} SegmentTree(const std::vector< Monoid > &v, const Func f, const Monoid &unity) { F = f; UNITY = unity; int sz = v.size(); n = 1; while (n < sz) n <<= 1; node.resize(n * 2 - 1, UNITY); for (int i = 0; i < sz; i++) node[i + n - 1] = v[i]; build(); } SegmentTree(int m, const Monoid &val, const Func f, const Monoid &unity) { F = f; UNITY = unity; n = 1; while (n < m) n <<= 1; node.resize(n * 2 - 1, UNITY); if (val != UNITY) { for (int i = 0; i < m; i++) node[i + n - 1] = val; build(); } } void set(int k, const Monoid &x) { node[n + k - 1] = x; } void build() { for (int i = n - 2; i >= 0; i--) node[i] = F(node[2 * i + 1], node[2 * i + 2]); } void update_query(int x, const Monoid &val) { if (x >= n || x < 0) return; x += n - 1; node[x] = val; while (x > 0) { x = (x - 1) >> 1; node[x] = F(node[2 * x + 1], node[2 * x + 2]); } } Monoid get_query(int l, int r) { Monoid L = UNITY, R = UNITY; if (l < 0) l = 0; if (r < 0) return UNITY; if (l >= n) return UNITY; if (r >= n) r = n; for (l += n, r += n; l < r; l >>= 1, r >>= 1) { if (l & 1) L = F(L, node[l++ - 1]); if (r & 1) R = F(node[--r - 1], R); } return F(L, R); } int binary_search(int l, int r, const std::function &f) { Monoid s = UNITY; int ret = _binary_search(l,r,f,s); return ret != n ? ret : -1; } Monoid operator[](int x) const { return node[n + x - 1]; } int size() { return n; } void print() { for (int i = 0; i < n; i++) { std::cout << i << "\t: " << node[n + i - 1] << std::endl; } } }; int main() { int n;cin >> n; vector> a(n); vector big(n),small(n); set st; for (int i = 0; i < n; i++) { cin >> a[i].first; a[i].second = i; } sort(a.begin(), a.end()); st.insert(-1); for (int i = 0; i < n; i++) { auto t = st.lower_bound(a[i].second); t--; small[a[i].second] = *t; st.insert(a[i].second); } st.clear(); sort(a.rbegin(), a.rend()); st.insert(-1); for (int i = 0; i < n; i++) { auto t = st.lower_bound(a[i].second); t--; big[a[i].second] = *t; st.insert(a[i].second); } SegmentTree seg1(n,0,[](int a,int b){return a+b;},0); SegmentTree seg2(n,0,[](int a,int b){return a+b;},0); stack> sta1, sta2; sort(a.begin(), a.end(), [](pair a,pair b){ return a.second < b.second; }); ll ans = 0; for (int i = 0; i < n; i++) { if (i != 0) { if (a[i-1].first < a[i].first) { ans += seg1.get_query(big[i]+1,i); } else { ans += seg2.get_query(small[i]+1,i); } } while(!sta1.empty() && sta1.top().first > a[i].first) { seg1.update_query(sta1.top().second,0); sta1.pop(); } seg1.update_query(a[i].second,1); sta1.push(a[i]); while(!sta2.empty() && sta2.top().first < a[i].first) { seg2.update_query(sta2.top().second,0); sta2.pop(); } seg2.update_query(a[i].second,1); sta2.push(a[i]); } cout << ans << endl; return 0; }