#include <bits/stdc++.h>

using namespace std;

typedef long long ll;

int arr[300005];

map<ll, ll> st;

int main() {
	int N;
	scanf("%d", &N);
	for (int i = 1; i <= N; ++i)
		scanf("%d", &arr[i]);

	ll mv = 0;
	ll ans = 0;
	for (int i = 1; i <= N; ++i) {
		if (i % 2 == 1) {
			st[-mv]++;
			mv -= arr[i];
			ans += st[-mv];
		}
		else {
			st[-mv]++;
			mv += arr[i];
			ans += st[-mv];
		}
	}

	printf("%lld\n", ans);

	return 0;
}
//...Bismillahir Rahmanir Rahim. . .

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>

using namespace std;
using namespace __gnu_pbds;

// typedefs...
typedef double db;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int, int> pii;
typedef vector<int> vi;
typedef vector<ll> vl;
typedef pair<ll, ll> pll;
typedef trie<string,null_type,trie_string_access_traits<>,pat_trie_tag,trie_prefix_search_node_update>pref_trie;
typedef tree<int, null_type, less<int>, rb_tree_tag, tree_order_statistics_node_update> oset;

// constants...
const double PI = acos(-1);
const ll mod = 1000000007; // 998244353;
const int MXS = 2e5+5;
const ll MXI = 1e9+5;
const ll MXL = 1e18+5;
const ll INF = 1e9+5;
const ll INFLL = 1e18+5;
const ll EPS = 1e-9;

// defines...
#define MP        make_pair
#define PB        push_back
#define fi         first
#define se         second
#define sz(x)      (int)x.size()
#define all(x)      begin(x), end(x)
#define si(a)       scanf("%d", &a)
#define sii(a, b)    scanf("%d%d", &a, &b)
#define ordered_set tree<ll,null_type,less_equal<ll>,rb_tree_tag,tree_order_statistics_node_update>
#define boost_      ios_base::sync_with_stdio(false),cin.tie(0),cout.tie(0);
#define iter_(i,n)    for (int i = 0; i < int(n); i++)
#define for_n(i, n)  for (int i = 1; i <= int(n); i++)
#define print_array(a) for(int i=0;i<n;i++)  cout<<a[i]<<" ";
#define rev(i,n)     for(int i=n;i>=0;i--)
#define itr          ::iterator
#define s_sort(s)    sort(s.begin(),s.end())
#define n_sort(a, n)    sort(a,a+n)
#define precise_impact cout<<setprecision(10)<<fixed;
#define endl         "\n"
// functions...
ll gcd(ll a, ll b){ while (b){ a %= b; swap(a, b);} return a;}
ll lcm(ll a, ll b){ return (a/gcd(a, b)*b);}
ll ncr(ll a, ll b){ ll x = max(a-b, b), ans=1; for(ll K=a, L=1; K>=x+1; K--, L++){ ans = ans * K; ans /= L;} return ans;}
ll bigmod(ll a,ll b){ if(b==0){ return 1;} ll tm=bigmod(a,b/2); tm=(tm*tm)%mod; if(b%2==1) tm=(tm*a)%mod; return tm;}
ll egcd(ll a,ll b,ll &x,ll &y){ if(a==0){ x=0; y=1; return b;} ll x1,y1; ll d=egcd(b%a,a,x1,y1); x=y1-(b/a)*x1; y=x1; return d;}
int main()
{
    ll n;
    cin>>n;
    map<ll,ll> m;
    ll ans=0,sum=0;
    m[0]=1;
    for(int i=0;i<n;i++)
    {
        ll x;
        cin>>x;
        if(i%2==0) sum+=x;
        else sum-=x;
        ans=ans+m[sum];
        m[sum]++;
    }
    cout<<ans<<endl;
}
