#include <algorithm>
#include <array>
#include <iostream>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <stack>
#include <vector>
using namespace std;
#define int long long
constexpr int MOD = 1000000000 + 7;

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

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

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

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