/*ver 7*/
#include <bits/stdc++.h>
using namespace std;
void init() {cin.tie(0);ios::sync_with_stdio(false);cout << fixed << setprecision(15);}
using ll = long long;
using ld = long double;
using vl = vector<ll>;
using vd = vector<ld>;
using vs = vector<string>;
using vb = vector<bool>;
using vvl = vector<vector<ll>>;
using vvd = vector<vector<ld>>;
using vvs = vector<vector<string>>;
using vvb = vector<vector<bool>>;
using pll = pair<ll,ll>;
using mll = map<ll,ll>;
template<class T> using V = vector<T>;
template<class T> using VV = vector<vector<T>>;
#define each(x,v) for(auto& x : v)
#define reps(i,a,b) for(ll i=(ll)a;i<(ll)b;i++)
#define rep(i,n) for(ll i=0;i<(ll)n;i++)
#define pb push_back
#define eb emplace_back
#define fi first
#define se second
#define mp make_pair
const ll INF = 1LL << 60;
#define CLR(mat,f) memset(mat, f, sizeof(mat))
#define IN(a, b, x) (a<=x&&x<=b)
#define UNIQUE(v) v.erase( unique(v.begin(), v.end()), v.end() ) //被り削除
#define debug cout << "line : " << __LINE__ << " debug" << endl;
#define ini(...) int __VA_ARGS__; in(__VA_ARGS__)
#define inl(...) long long __VA_ARGS__; in(__VA_ARGS__)
#define ind(...) long double __VA_ARGS__; in(__VA_ARGS__)
#define ins(...) string __VA_ARGS__; in(__VA_ARGS__)
#define inc(...) char __VA_ARGS__; in(__VA_ARGS__)
void in(){}
template <typename T,class... U> void in(T &t,U &...u){ cin >> t; in(u...);}
template <typename T> void in1(T &s) {rep(i,s.size()){in(s[i]);}}
template <typename T> void in2(T &s,T &t) {rep(i,s.size()){in(s[i],t[i]);}}
template <typename T> void in3(T &s,T &t,T &u) {rep(i,s.size()){in(s[i],t[i],u[i]);}}
template <typename T> void in4(T &s,T &t,T &u,T &v) {rep(i,s.size()){in(s[i],t[i],u[i],v[i]);}}
template <typename T> void in5(T &s,T &t,T &u,T &v,T &w) {rep(i,s.size()){in(s[i],t[i],u[i],v[i],w[i]);}}
void out(){cout << endl;}
template <typename T,class... U> void out(const T &t,const U &...u){cout << t; if(sizeof...(u)) cout << " "; out(u...);}
void die(){cout << endl;exit(0);}
template <typename T,class... U> void die(const T &t,const U &...u){cout << t; if(sizeof...(u)) cout << " "; die(u...);}
template <typename T> void outv(T s) {rep(i,s.size()){if(i!=0)cout<<" ";cout<<s[i];}cout<<endl;}
template <typename T> void out1(T s) {rep(i,s.size()){out(s[i]);}}
template <typename T> void out2(T s,T t) {rep(i,s.size()){out(s[i],t[i]);}}
template <typename T> void out3(T s,T t,T u) {rep(i,s.size()){out(s[i],t[i],u[i]);}}
template <typename T> void out4(T s,T t,T u,T v) {rep(i,s.size()){out(s[i],t[i],u[i],v[i]);}}
template <typename T> void out5(T s,T t,T u,T v,T w) {rep(i,s.size()){out(s[i],t[i],u[i],v[i],w[i]);}}
#define all(v) (v).begin(),(v).end()
#define rall(v) (v).rbegin(),(v).rend()
template <typename T> T allSum(vector<T> a){T ans=T();each(it,a)ans+=it;return ans;}
ll ceilDiv(ll a,ll b) {return (a+b-1)/b;}
ld dist(pair<ld,ld> a, pair<ld,ld> b){return sqrt(abs(a.fi-b.fi)*abs(a.fi-b.fi)+abs(a.se-b.se)*abs(a.se-b.se));} // ２点間の距離 
ll gcd(ll a, ll b) { return b != 0 ? gcd(b, a % b) : a; }
ll lcm(ll a,ll b){ return a / gcd(a,b) * b;}
template <class A, class B> inline bool chmax(A &a, const B &b) { return b > a && (a = b, true); }
template <class A, class B> inline bool chmin(A &a, const B &b) { return b < a && (a = b, true); }
#define YES(n) ((n) ? "YES" : "NO"  )
#define Yes(n) ((n) ? "Yes" : "No"  )
#define yes(n) ((n) ? "yes" : "no"  )

int main(){
	init();
	inl(n);
	V<ll> a(n);
	in1(a);
	V<ll> goal(n);
	V<ll> l(n),r(n);
	ll now=0;
	rep(i,n){
		now+=a[i];
		goal[i]=now;
		if(i==0){
			l[i]=min(0LL,now);
			r[i]=max(0LL,now);
		}else{
			l[i]=min(l[i-1],now);
			r[i]=max(r[i-1],now);
		}
	}
	ll ansMax=0,ansMin=0;
	now=0;
	rep(i,n){
		chmin(ansMin,now+l[i]);
		chmax(ansMax,now+r[i]);
		now+=goal[i];
	}
	out(ansMax);
	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;
}
