#pragma GCC target("avx2")
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")

#include <bits/stdc++.h>

using namespace std;
#define rep(i,n) for(int i=0;i<n;++i)
#define rep1(i,n) for(int i=1;i<=n;++i)
#define debug(output) cout<<#output<<"= "<<output<<endl
using lint = long long;
typedef pair<int,int> P;
const lint linf=1e18+7;
const lint inf=1e9+7;
const int MOD=1000000007;
template<class T>
class SegTree{
    int n;
    vector<T> node;
    T e;
    function<T(T,T)> operation;
    function<T(T,T)> update;
    public:
    SegTree(int _n,T _e,function<T(T,T)> _operation,function<T(T,T)> _update):n(_n),e(_e),operation(_operation),update(_update){node.resize(n*2,e);}
    void change(int i,T x){
        i+=n;
        node[i]=update(node[i],x);
        while(i>1){
            i>>=1;
            node[i]=operation(node[i<<1|0],node[i<<1|1]);
        }
    }
    T get(int l,int r){
        T a=e;
        T b=e;
        l+=n;r+=n;
        while(l<r){
            if(l&1)a=operation(a,node[l++]);
            if(r&1)b=operation(node[--r],b);
            l>>=1;r>>=1;
        }
        return operation(a,b);
    }
    void input(vector<T>& _input){
        for(int i=0;i<n;++i){
            change(i,_input[i]);
        }
    }
};
signed main(){
  cin.tie(0);
  ios::sync_with_stdio(false);
  int n;cin>>n;
  vector<int> a(n);
  rep(i,n)cin>>a[i];
  auto op=[](int a,int b){return max(a,b);};
  auto op2=[](P a,P b){
    vector<int> v={a.first,a.second,b.first,b.second};
    sort(v.begin(),v.end());
    P res={v[0],v[1]};
    return res;
  };
  SegTree<int> M(n,0,op,op);
  M.input(a);
  SegTree<P> m(n,{inf,inf},op2,op2);
  vector<P> b(n);
  rep(i,n){
    b[i]={a[i],inf};
  }
  m.input(b);
  lint res=0;
  rep(i,n-1){
    int l=i+1;int r=n;
    while(r-l>1){
      int mid=(r+l)/2;
      auto hoge=m.get(i,mid+1);
      if(M.get(i,mid+1)<=hoge.first+hoge.second)l=mid;
      else r=mid;
    }
    res+=l-i;
  }
  cout<<res<<"\n";
  return 0;
}