using namespace std;
#include<fstream>
const int MAX_N = 100007;
int S[MAX_N], N;
int main()
{
	ifstream in("numarare.in"); ofstream out("numarare.out");
	in>>N;
	int sol = 0, i, j;
	for(i = 1; i <= N; ++i)
		in>>S[i];
	for(i = 1; i < N; ++i)
	{
		for(j = 0; i - j > 0 && i + j + 1 <= N; ++j)
			if( S[i] + S[i+1] == S[i - j] + S[i + j + 1] ) ++sol;
			else break;
	}	
	out<<sol<<"\n";
	return 0;
}