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#include <algorithm>
#include <iostream>
using namespace std;

const int MAXN = 300000;
const int MOD = 1000000007;

#define FOR(i, n) for(int i = 0, __n = (n); i < __n; i++)


struct Node {
  int a, b;
  Node * L, *R;
  int v;
  int s[2];

  void init() {
    v = 0;
    s[0] = s[1] = 0;
    L = R = nullptr;
  }

  Node(int a, int b): a(a), b(b) { init(); }
  Node(): a(0), b(MOD) { init(); }

  int mid() const {
    return (b-a)/2 + a;
  }

  Node * getL() {
    if(L == nullptr) L = new Node(a, mid());
    return L;
  }

  Node * getR() {
    if(R == nullptr) R = new Node(mid(), b);
    return R;
  }

  void add(int p, int val) {
    v = (v + val)%MOD;
    s[p%2] = (s[p%2] + val)%MOD;
    if(b-a > 1) {
      if(p < mid()) {
        getL()->add(p, val);
      } else {
        getR()->add(p, val);
      }
    }
  }

  int total(int a1, int b1, int p) {
    if(a1<=a && b1 >=b) return s[p];
    if(a1 >= b || b1 <= a) return 0;
    else {
      int sum = 0;
      if (L) sum += L->total(a1, b1, p);
      if (R) sum += R->total(a1, b1, p);
      return sum%MOD;
    }
  }


};


int T[MAXN];

int main() {
  ios_base::sync_with_stdio(0);

  int n; cin >> n;
  FOR(i, n) {
    cin >> T[i];
  }

  Node root;

  root.add(0, 1);

  int sum = 0;
  int ile;
  FOR(i, n) {
    sum += T[i];
    sum %= MOD;
    ile = (root.total(0, MOD-sum, sum%2) + root.total(MOD-sum, MOD, !(sum%2)))%MOD;

    root.add(MOD-sum, ile);
  }
  cout << ile << endl;

}