#pragma GCC optimize ("Ofast,unroll-loops")
#pragma GCC optimize("no-stack-protector,fast-math")

#include <bits/stdc++.h>

using namespace std;

constexpr int M = 998244353;

#define fastio ios::sync_with_stdio(false), cin.tie(0), cout.tie(0);
#define int long long
#define pii pair<int, int>
#define fi first
#define se second
#define SZ(x) ((int)(x.size()))

#ifdef int
#define INF 0x3f3f3f3f3f3f3f3f
#define INF2 (int)(0xcfcfcfcfcfcfcfcf)
#else
#define INF 0x3f3f3f3f
#define INF2 0xcfcfcfcf
#endif

signed main() {
    fastio
    int n;
    cin >> n;
    map<int, int> cnt;
    int sum = 0;
    cnt[0]++;
    int ans = 0;
    for (int i = 1; i <= n; i++) {
        int x;
        cin >> x;
        if (i & 1) sum -= x;
        else sum += x;
        if (cnt.count(sum)) ans += cnt[sum];
        cnt[sum]++;
    }
    cout << ans << "\n";
    return 0;
}
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
using namespace std;
#ifdef ENABLE_DEBUG
#define dump(a) cerr<<#a<<"="<<(a)<<endl
#define dumparr(a,n) cerr<<#a<<"["<<(n)<<"]="<<(a[n])<<endl
#else
#define dump(a) 
#define dumparr(a,n) 
#endif
#define FOR(i, a, b) for(ll i = (ll)a;i < (ll)b;i++)
#define For(i, a) FOR(i, 0, a)
#define REV(i, a, b) for(ll i = (ll)b-1LL;i >= (ll)a;i--)
#define Rev(i, a) REV(i, 0, a)
#define REP(a) For(i, a)
#define SIGN(a) (a==0?0:(a>0?1:-1))

typedef long long int ll;
typedef unsigned long long ull;
typedef unsigned int uint;
typedef pair<ll, ll> pll;
typedef pair<ll,pll> ppll;
typedef vector<ll> vll;
typedef long double ld;
typedef pair<ld,ld> pdd;

pll operator+(pll a,pll b){
  return pll(a.first+b.first,a.second+b.second);
}
pll operator-(pll a,pll b){
  return pll(a.first-b.first,a.second-b.second);
}
pll operator*(ll a,pll b){
  return pll(b.first*a,b.second*a);
}
const ll INF=(1LL<<60);
#if __cplusplus<201700L
ll gcd(ll a, ll b) {
  a=abs(a);
  b=abs(b);
  if(a==0)return b;
  if(b==0)return a;
  if(a < b) return gcd(b, a);
  ll r;
  while ((r=a%b)) {
    a = b;
    b = r;
  }
  return b;
}
#endif
template<class T>
bool chmax(T& a,const T& b){
  if(a<b){
    a=b;
    return true;
  }
  return false;
}
template<class T>
bool chmin(T& a,const T& b){
  if(a>b){
    a=b;
    return true;
  }
  return false;
}
template<class S,class T>
std::ostream& operator<<(std::ostream& os,pair<S,T> a){
  os << "(" << a.first << "," << a.second << ")";
  return os;
}
template<class T>
std::ostream& operator<<(std::ostream& os,vector<T> a){
  os << "[ ";
  REP(a.size()){
    os<< a[i] << " ";
  }
  os<< "]";
  return os;
}
template<class T>
std::ostream& operator<<(std::ostream& os,set<T> a){
  os << "{ ";
  for(auto itr=a.begin();itr!=a.end();++itr){
    os<< *itr << " ";
  }
  os<< "}";
  return os;
}
template<class T>
void ans_array(T begin,T end){
  auto itr=begin;
  cout<<*itr;
  ++itr;
  for(;itr!=end;++itr){
    cout<<' '<<*itr;
  }
  cout<<endl;
}
template<class T>
void ans_array_newline(T begin,T end){
  for(auto itr=begin;itr!=end;++itr){
    cout<<*itr<<endl;
  }
}


void solve(long long N, std::vector<long long> A){
  REP(N){
    if(i%2){
      A[i]=-A[i];
    }
  }
  vector<ll> sumA(N+1);
  REP(N){
    sumA[i+1]=sumA[i]+A[i];
  }
  map<ll,ll> mp;
  REP(N+1){
    mp[sumA[i]]++;
  }
  ll ans=0;
  for (auto &&i : mp)
  {
    ans+=i.second*(i.second-1)/2;
  }
  cout<<ans<<endl;
}

int main(){
  cout<<setprecision(1000);
  long long N;
    scanf("%lld", &N);
    std::vector<long long> A(N);
    for(int i = 0 ; i < N ; i++){
        scanf("%lld", &A[i]);
    }
  solve(N, std::move(A));
  return 0;
}
