#include <bits/stdc++.h>
#define pb push_back

using namespace std;

ifstream fin("numarare.in");
ofstream fout("numarare.out");

void debug_out() { cerr << '\n'; }
template <typename Head, typename... Tail> void debug_out(Head H, Tail... T) { cerr << " " << H; debug_out(T...);}
#define dbg(...) cerr << #__VA_ARGS__ << " ->", debug_out(__VA_ARGS__)
#define dbg_v(x, n) do{cerr<<#x"[]: ";for(int _=0;_<n;++_)cerr<<x[_]<<" ";cerr<<'\n';}while(0)
#define dbg_ok cerr<<"OK!\n"

typedef pair<int,int> pii;
typedef long long int ll;
typedef long double ld;

const int DMAX = 1e5+10;

int V[DMAX];
int d2[DMAX];

int n;
ll ans;

int main(){
    ios_base::sync_with_stdio(false);
    cin.tie(0);

    int t,i,j;
    int l,r,k,suma;

    fin>>n;
    for(i=0;i<n;i++)
        fin>>V[i];

    for(i=0,l=0,r=-1;i<n;i++){
        k=(i>r)?0:min(d2[l+r-i+1],r-i+1);
        if(i == 0)
            continue;
        suma=V[i]+V[i-1];
        while(0 <= i-k-1 && i+k < n && V[i-k-1]+V[i+k]==suma)
            k++;
        d2[i]=k--;
        ans+=d2[i];
        if(i+k > r){
            l=i-k-1;
            r=i+k;
        }
    }
    fout<<ans<<'\n';

    return 0;
}