const MOD: usize = 1e9 as usize + 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 mut a: Vec<usize> = a.trim().split_whitespace().map(|s| s.parse().unwrap()).collect();

    while a.len() > 1 {
        let mut na = Vec::with_capacity(a.len()-1);
        for i in 1..a.len() {
            na.push((a[i-1] + a[i]) % MOD);
        }
        a = na;
    }
    println!("{}", a[0]);
}