#include <bits/stdc++.h>
#define rep(i, a, n) for (int i = a; i < n; i++)
#define repr(i, a, n) for (int i = n - 1; i >= a; i--)
using namespace std;
using ll = long long;
using P = pair<int, int>;
template <typename T> void chmin(T &a, T b) { a = min(a, b); }
template <typename T> void chmax(T &a, T b) { a = max(a, b); }

const int MOD = 1000000007;

int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);

  int n;
  cin >> n;
  vector<ll> a(n);
  rep(i, 0, n) cin >> a[i];

  int c = 0;
  vector<ll> next(n, 0);
  int t = n - 1;
  while (t--) {
    rep(i, 0, t + 1) {
      next[c] = (a[i] + a[i + 1]) % MOD;
      c++;
    }
    c = 0;
    a = next;
  }

  cout << next[0] % MOD << endl;
}