const MOD: isize = 1e9 as isize + 7;

fn main() {
    let mut n = String::new();
    std::io::stdin().read_line(&mut n).ok();
    let n: usize = n.trim().parse().unwrap();
    let mut a = String::new();
    std::io::stdin().read_line(&mut a).ok();
    let a: Vec<isize> = a.trim().split_whitespace().map(|s| s.parse().unwrap()).collect();

    let mut dp = vec![vec![0isize; 2]; n];
    dp[0][1] = a[0];
    for i in 0..n-1 {
        dp[i+1][0] = (dp[i][0] * 3 + dp[i][1] * 2) % MOD;
        dp[i+1][1] = dp[i][1] * a[i+1] % MOD;
    }
    println!("{}", (dp[n-1][0] + dp[n-1][1]) % MOD);
}