#include<bits/stdc++.h>
using namespace std;
ifstream f("numarare.in");
ofstream g("numarare.out");
int n,v[100002],sol;
int main()
{
    f>>n;
    for(int i=1;i<=n;++i)
        f>>v[i];
    for(int i=1;i<n;++i)
    {
        int s=v[i]+v[i+1];
        int st=i;
        int sf=i+1;
        while(v[st]+v[sf]==s)
        {
            ++sol;
            --st;
            ++sf;
            if(!st || sf>n)
                break;
        }
    }
    g<<sol;
    return 0;
}