#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const ll MOD = 1e9 + 7;

int main() {
  int n;
  cin >> n;
  vector<ll> a(n);
  for (int i = 0; i < n; ++i) cin >> a[i];

  while (a.size() > 1) {
    vector<ll> b(a.size() - 1);
    for (int i = 1; i < a.size(); ++i) {
      b[i - 1] = a[i] + a[i - 1];
      b[i - 1] %= MOD;
    }
    a = b;
  }
  cout << a[0] << '\n';
  return 0;
}