#include #define rep(i,a,b) for(int i=a;i=b;i--) #define fore(i,a) for(auto &i:a) #define all(x) (x).begin(),(x).end() //#pragma GCC optimize ("-O3") using namespace std; void _main(); int main() { cin.tie(0); ios::sync_with_stdio(false); _main(); } typedef long long ll; const int inf = INT_MAX / 2; const ll infl = 1LL << 60; templatebool chmax(T& a, const T& b) { if (a < b) { a = b; return 1; } return 0; } templatebool chmin(T& a, const T& b) { if (b < a) { a = b; return 1; } return 0; } //--------------------------------------------------------------------------------------------------- #ifdef _MSC_VER inline unsigned int __builtin_clz(unsigned int x){unsigned long r;_BitScanReverse(&r,x);return 31-r;} #endif // _MSC_VER template struct SparseTable { // [L,R) const V def = make_pair(-1,-1); inline V comp(V a, V b) { return max(a,b); } int n; vector a, b[22]; inline int __lg(int x) { return 32 - 1 - __builtin_clz(x); } void init(vector v) { int nn = v.size(); n = 1; while (n < nn) n *= 2; a.resize(n); rep(i, 0, 22) b[i].resize(n); rep(i, 0, nn) a[i] = v[i]; int d = 1 << __lg(n - 1), e = d << 1; for (int h = 0, f; (f = 1 << h) <= d; ++h) { for (int i = f, r = f << 1; i < e; i += r) { b[h][i - 1] = a[i - 1]; for (int j = i - 2; j >= i - f; --j) b[h][j] = comp(b[h][j + 1], a[j]); b[h][i] = a[i]; for (int j = i + 1; j < i + f; ++j) b[h][j] = comp(b[h][j - 1], a[j]); } } } V get(int L,int R){assert(0<=L&&L<=R);if(L==R)return def;R--;if(L==R)return a[L];int h=__lg(L^R); return comp(b[h][L],b[h][R]);}}; int defmin = inf; template struct SegTreeMin { //[l,r) V comp(V& l, V& r) { return min(l, r); }; vector val; SegTreeMin() { val = vector(NV * 2, defmin); } V get(int x, int y, int l = 0, int r = NV, int k = 1) { if (r <= x || y <= l)return defmin; if (x <= l && r <= y)return val[k]; auto a = get(x, y, l, (l + r) / 2, k * 2); auto b = get(x, y, (l + r) / 2, r, k * 2 + 1); return comp(a, b); } void update(int i, V v) { i += NV; val[i] = v; while (i>1) i >>= 1, val[i] = comp(val[i * 2], val[i * 2 + 1]); } void add(int i, V v) { update(i, val[i + NV] + v); } V operator[](int x) { return get(x, x + 1); } }; #define def 0 template struct SegTreeMax { //[l,r) V comp(V& l, V& r) { return max(l, r); }; vector val; SegTreeMax() { val = vector(NV * 2, def); } V get(int x, int y, int l = 0, int r = NV, int k = 1) { if (r <= x || y <= l)return def; if (x <= l && r <= y)return val[k]; auto a = get(x, y, l, (l + r) / 2, k * 2); auto b = get(x, y, (l + r) / 2, r, k * 2 + 1); return comp(a, b); } void update(int i, V v) { i += NV; val[i] = v; while (i > 1) i >>= 1, val[i] = comp(val[i * 2], val[i * 2 + 1]); } void add(int i, V v) { update(i, val[i + NV] + v); } V operator[](int x) { return get(x, x + 1); } }; /*---------------------------------------------------------------------------------------------------             ∧_∧       ∧_∧  (´<_` )  Welcome to My Coding Space!      ( ´_ゝ`) /  ⌒i @hamayanhamayan0     /   \    | |     /   / ̄ ̄ ̄ ̄/  |   __(__ニつ/  _/ .| .|____      \/____/ (u ⊃ ---------------------------------------------------------------------------------------------------*/ int N, A[101010]; SparseTable> st; //--------------------------------------------------------------------------------------------------- int pre[20][101010]; int post[20][101010]; SegTreeMin stmin; SegTreeMax stmax; void init() { rep(p, 0, 20) rep(idx, 0, 101010) pre[p][idx] = 0; rep(i, 0, N) { pre[0][i + 1] = stmax.get(0, A[i]); stmax.update(A[i], i + 1); } rep(p, 1, 20) rep(idx, 0, N + 1) pre[p][idx] = pre[p - 1][pre[p - 1][idx]]; defmin = N + 1; rep(p, 0, 20) rep(idx, 0, 101010) post[p][idx] = N + 1; rrep(i, N - 1, 0) { post[0][i + 1] = stmin.get(0, A[i]); stmin.update(A[i], i + 1); } rep(p, 1, 20) rep(idx, 0, N + 1) post[p][idx] = post[p - 1][post[p - 1][idx]]; } int getpre(int idx, int cnt) { int res = idx; rep(p, 0, 20) if (cnt & (1 << p)) res = pre[p][res]; return res; } int getpost(int idx, int cnt) { int res = idx; rep(p, 0, 20) if (cnt & (1 << p)) res = post[p][res]; return res; } //--------------------------------------------------------------------------------------------------- ll ans = 0; void f(int L, int R) { if (L == R) return; if (L + 1 == R) return; auto ma = st.get(L, R); int C = ma.second; { int ok = 0, ng = N + 1; while (ok + 1 != ng) { int md = (ok + ng) / 2; if (L <= getpre(C, md)) ok = md; else ng = md; } ans += ok; } { int ok = 0, ng = N + 1; while (ok + 1 != ng) { int md = (ok + ng) / 2; if (getpost(C, md) < R) ok = md; else ng = md; } ans += ok; } f(L, C); f(C + 1, R); } //--------------------------------------------------------------------------------------------------- void _main() { cin >> N; rep(i, 0, N) cin >> A[i]; init(); vector> dic; dic.push_back({ -1, -1 }); rep(i, 0, N) dic.push_back({ A[i], i + 1 }); st.init(dic); f(1, N + 1); cout << ans << endl; }