#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <algorithm>
#include <vector>

using namespace std;

#define file_in "numarare.in"
#define file_out "numarare.out"

#define nmax 101001

int n;
int s[nmax];

void citire()
{
    int i;
    freopen(file_in,"r",stdin);
    freopen(file_out,"w",stdout);

    scanf("%d", &n);
    for (i=1;i<=n;++i)
          scanf("%d", &s[i]);

}

void solve()
{
    int i,j,k,nr;
    nr=0;

    for (i=1;i<n;++i)
    {
        j=i;
        k=i+1;
        int x=s[k]+s[j];
        nr++;
        while(j>1 && k<n && x==s[j-1]+s[k+1])
        {
            nr++;
            j--;
            k++;
        }
    }
    printf("%d\n", nr);
}

int main()
{
    citire();
    solve();

    fclose(stdin);
    fclose(stdout);

    return 0;
}