#include <bits/stdc++.h>

using namespace std;

vector<int64_t> newarr(vector<int64_t> &orig) {
    vector<int64_t> newarr;
    int sz = orig.size();
    for (int j = 0; j < sz; j++) {
        if (j + 1 < sz) {
            int64_t one = orig[j];
            int64_t other = orig[j + 1];
            newarr.push_back(one + other);
        }
    }
    return newarr;
}

int main(int argc, char *argv[]) {
    int N;
    cin >> N;

    vector<int64_t> arr(N);
    for (int i = 0; i < N; i++) {
        cin >> arr[i];
    }

    while (arr.size() != 1) {
        arr = newarr(arr);
    }

    int64_t ans = arr[0] % 1000000007;
    cout << ans << endl;
	return 0;
}