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

int main() {
  int N, M = 1e9+7;
  cin >> N;
  vector<long> A(N);
  for (int i = 0; i < N; i++) cin >> A.at(i);
  while (A.size() > 1) {
    vector<long> tmp;
    for (int i = 0; i + 1 < A.size(); i++) {
      tmp.push_back((A.at(i) + A.at(i + 1)) % M);
    }
    A = tmp;
  }
  cout << A.at(0) << "\n";
}