#include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include using namespace std; using namespace atcoder; typedef long long ll; #define rep(i, n) for (int i = 0; i < (int)(n); i++) #define repr(i, n) for (int i = (int)(n) - 1; i >= 0; i--) #define repk(i, k, n) for (int i = k; i < (int)(n); i++) #define all(v) v.begin(), v.end() #define mod1 1000000007 #define mod2 998244353 #define mod3 100000007 #define vi vector #define vs vector #define vc vector #define vl vector #define vb vector #define vvi vector> #define vvc vector> #define vvl vector> #define vvb vector> #define vvvi vector>> #define vvvl vector>> #define pii pair #define pil pair #define pli pair #define pll pair #define vpii vector> #define vpll vector> #define vvpii vector>> #define vvpll vector>> // using mint = modint998244353; template void debug(T e) { cerr << e << endl; } template void debug(vector &v) { rep(i, v.size()) { cerr << v[i] << " "; } cerr << endl; } template void debug(vector> &v) { rep(i, v.size()) { rep(j, v[i].size()) { cerr << v[i][j] << " "; } cerr << endl; } } template void debug(vector> &v) { rep(i, v.size()) { cerr << v[i].first << " " << v[i].second << endl; } } template void debug(set &st) { for (auto itr = st.begin(); itr != st.end(); itr++) { cerr << *itr << " "; } cerr << endl; } template void debug(multiset &ms) { for (auto itr = ms.begin(); itr != ms.end(); itr++) { cerr << *itr << " "; } cerr << endl; } template void debug(map &mp) { for (auto itr = mp.begin(); itr != mp.end(); itr++) { cerr << itr->first << " " << itr->second << endl; } } void debug_out() { cerr << endl; } template void debug_out(Head H, Tail... T) { cerr << H << " "; debug_out(T...); } using mint = modint1000000007; void debug_mint1(vector &vec) { for (int i = 0; i < vec.size(); i++) { cerr << vec[i].val() << " "; } cerr << endl; } void debug_mint2(vector> &vec) { for (int i = 0; i < vec.size(); i++) { for (int j = 0; j < vec[i].size(); j++) { cerr << vec[i][j].val() << " "; } cerr << endl; } } ll INF = 100000000023; ll op_max(ll a, ll b) { return max(a, b); } ll e_max() { return -INF; } struct S { ll first; ll second; }; S op_min(S a, S b) { if (a.second <= b.first) { return a; } else if (b.second <= a.first) { return b; } return S{min(a.first, b.first), max(a.first, b.first)}; } S e_min() { return S{INF, INF}; } int main() { ll N; cin >> N; vector a(N); for (ll i = 0; i < N; i++) { cin >> a[i]; } segtree seg1(N); segtree seg2(N); for (ll i = 0; i < N; i++) { seg1.set(i, a[i]); seg2.set(i, S{a[i], INF}); } ll ans = 0; for (ll i = 0; i < N - 1; i++) { ll ok = i + 1; ll ng = N; while (ng - ok > 1) { ll mid = (ok + ng) / 2; ll p1 = seg1.prod(i, mid + 1); S p2 = seg2.prod(i, mid + 1); if (p2.first + p2.second >= p1) { ok = mid; } else { ng = mid; } } ans += ok - i; } cout << ans << endl; }