%1e9+7问题收录

#include <iostream>
#include <cstdio>
using namespace std;
const int M = 1e9 + 7;
#define ll long long
int main()
{
    int n;
    ll x, ans = 0;
    scanf("%d", &n);
    for (int i = 1; i <= n; i++)
    {
        scanf("%lld", &x);
        ans += ans * x % M + x;
        ans %= M;
    }
    printf("%lld", ans);
    return 0;
}