const DIVISOR: u64 = 10u64.pow(9) + 7;

fn main() {
    let mut xx = String::new();
    std::io::Read::read_to_string(&mut std::io::stdin(), &mut xx).ok();
    let mut xx: Vec<u64> = xx.split_whitespace().skip(1).flat_map(str::parse).collect();

    while xx.len() >= 2 {
        xx = xx.windows(2).map(|x| (x[0] + x[1]) % DIVISOR).collect();
    }

    println!("{}", xx[0]);
}