#include <iostream>
#include <fstream>

using namespace std;

const char iname[] = "numarare.in";
const char oname[] = "numarare.out";
const int nmax = 100005;

ifstream fin(iname);
ofstream fout(oname);

int N, A[nmax], i, j, k, sol, t;

int main()
{
	fin >> N;
	for(i = 1; i <= N; i ++)
		fin >> A[i];
	for(i = 1; i <= N; i ++)
		for(j = i  ; j <= N ; j ++)
		{	
			if((j - i) % 2 == 1)
			{
				t = 1;
				for(k = 0; i + k - 1 >= 1 && j - k + 1 >= 1 && i + k >=1  && j - k >= 1 && i + k - 1 <= N && j - k + 1 <= N && i + k <= N  && j - k <= N ; k ++)
					if(A[i + k] + A[j - k] != A[i + k - 1] + A[j - k + 1])
						t = 0;
				if(t == 1)
					sol ++;
			}
		}
		
	fout << sol;
	return 0;
}