#include <bits/stdc++.h>
#define pt(sth) cout << sth << "\n"
#define itr(x,c) for(auto x=c.begin();x!=c.end();x++)
#define ritr(x,c) for(auto x=c.rbegin();x!=c.rend();x++)
#define all(a) (a.begin()),(a.end())
#define rall(a) (a.rbegin()),(a.rend())
#define __builtin_popcount(v) popcount(v)
using namespace std;
#include <atcoder/all>
using namespace atcoder;
typedef long long ll;
typedef pair<ll, ll> pll;
template<class T>bool chmax(T &a, const T &b) {if(a<b) {a=b; return 1;} return 0;}
template<class T>bool chmin(T &a, const T &b) {if(b<a) {a=b; return 1;} return 0;}
static const ll INF=1e18;
static const ll MAX=101010;
static const ll MOD=1e9+7;
//static const ll MOD=998244353;
//for(i=0;i<N;i++) cin>>a[i];

typedef vector<ll> v1d;
typedef vector<v1d> v2d;
typedef vector<v2d> v3d;
typedef vector<v3d> v4d;



struct S{ll M, m1, m2;};
S op(S a, S b){
  ll M=max(a.M,b.M);
  ll m1=min(a.m1,b.m1);
  ll m2=a.m1<b.m1?min({b.m1,a.m2,b.m2}):min({a.m1,a.m2,b.m2});
  return {M,m1,m2};
}
S e(){return {-INF,INF,INF};}

bool f(S a){
  return a.M<=a.m1+a.m2;
}


int main(void) {
  ll i,j,k;
  
  ll N;cin>>N;
  segtree<S,op,e> seg(N);
  for(i=0;i<N;i++){
    ll a;cin>>a;
    seg.set(i,{a,a,INF});
  }
  
  ll ans=0;
  for(i=0;i<N-1;i++){
    ll r=seg.max_right<f>(i);
    ans+=r-1-i;
  }
  
  pt(ans);
  
  
}