#include <iostream>
#include <fstream>
#include <vector>
#include <algorithm>
#include <cstring>
#include <map>
using namespace std;
typedef long long ll;
const int maxn = 1e5 + 10;

int main() {
    ios_base::sync_with_stdio(false);
    int n;
    cin >> n;

    vector<ll> v(n + 1);
    for(int i = 1; i <= n; i++) {
        cin >> v[i];
    }
    vector<ll> pref_sum(n + 1, 0);
    map<ll, ll> freq;

    freq[0]++;
    ll sum = 0;
    for(int i = 1; i <= n; i++) {
        if(i % 2 == 1) {
            sum += v[i];
        }
        else {
            sum -= v[i];
        }
        pref_sum[i] = sum;
        freq[sum]++;
    }

    ll res = 0;
    for(pair<ll, ll> p: freq) {
        if(p.second >= 2) {
            res += (p.second * (p.second - 1)) / 2;
        }
    }
    cout << res << endl;


    return 0;
}