#include <iostream>
#include <vector>
using namespace std;
#include <atcoder/modint>
using mint = atcoder::modint1000000007;

int main() {
    int N;
    cin >> N;
    mint ret = 0, prod = 1;

    const mint d23 = mint(2) / 3;
    for (int i = 0; i < N; i++) {
        ret *= 3;
        int a;
        cin >> a;
        prod *= mint(a);
        ret += prod * (i == N - 1 ? 1 : d23);
    }
    cout << ret.val() << '\n';
}