#include <bits/stdc++.h>
using namespace std;

int main() {
  int N;
  cin >> N;
  vector<int> A(N), B;

  for (int i = 0; i < N; i++) cin >> A.at(i);

  while (A.size() != 1) {
    for (int i = 0; i < (int)A.size() - 1; i++)
      B.push_back((A.at(i) + A.at(i + 1)) % 1000000007);
    swap(A, B);
    B.clear();
  }

  cout << A.at(0) << endl;
}