use std::collections::*;
use std::io::*;
use std::*;
// template {{{
macro_rules! get {
    ($($t:tt),*; $n:expr) => {
        {
            let stdin = std::io::stdin();
            let ret = std::io::BufRead::lines(stdin.lock()).take($n).map(|line| {
                let line = line.unwrap();
                let mut it = line.split_whitespace();
                _get!(it; $($t),*)
            }).collect::<Vec<_>>();
            ret
        }
    };
    ($($t:tt),*) => {
        {
            let mut line = String::new();
            std::io::stdin().read_line(&mut line).unwrap();
            let mut it = line.split_whitespace();
            _get!(it; $($t),*)
        }
    };
}
macro_rules! _get {
    ($it:ident; [char]) => {
        _get!($it; String).chars().collect::<Vec<_>>()
    };
    ($it:ident; [u8]) => {
        _get!($it; String).bytes().collect::<Vec<_>>()
    };
    ($it:ident; usize1) => {
        $it.next().unwrap().parse::<usize>().unwrap_or_else(|e| panic!("{}", e)) - 1
    };
    ($it:ident; [usize1]) => {
        $it.map(|s| s.parse::<usize>().unwrap_or_else(|e| panic!("{}", e)) - 1).collect::<Vec<_>>()
    };
    ($it:ident; [$t:ty]) => {
        $it.map(|s| s.parse::<$t>().unwrap_or_else(|e| panic!("{}", e))).collect::<Vec<_>>()
    };
    ($it:ident; $t:ty) => {
        $it.next().unwrap().parse::<$t>().unwrap_or_else(|e| panic!("{}", e))
    };
    ($it:ident; $($t:tt),+) => {
        ($(_get!($it; $t)),*)
    };
}
mod modint {
    use std::ops::*;
    pub trait Mod: Copy {
        fn m() -> u64;
    }
    #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug)]
    pub struct Modint<M> {
        x: u64,
        phantom: std::marker::PhantomData<M>,
    }
    impl<M: Mod> Modint<M> {
        pub fn new(x: i64) -> Self {
            Modint::new_internal(((x % (M::m() as i64) + M::m() as i64) % M::m() as i64) as u64)
        }
        fn new_internal(x: u64) -> Self {
            Modint {
                x,
                phantom: std::marker::PhantomData,
            }
        }
        pub fn pow(self, mut e: u64) -> Self {
            let mut res = Modint::new_internal(1);
            let mut acc = self;
            while e > 0 {
                if e % 2 != 0 {
                    res *= acc;
                }
                acc *= acc;
                e /= 2;
            }
            res
        }
        pub fn inv(self) -> Self {
            self.pow(M::m() - 2)
        }
    }
    impl<M: Mod, T: Into<Modint<M>>> Add<T> for Modint<M> {
        type Output = Self;
        fn add(self, other: T) -> Self {
            let mut sum = self.x + other.into().x;
            if sum >= M::m() {
                sum -= M::m();
            }
            Modint::new_internal(sum)
        }
    }
    impl<M: Mod, T: Into<Modint<M>>> Sub<T> for Modint<M> {
        type Output = Self;
        fn sub(self, other: T) -> Self {
            let mut diff = self.x as i64 - other.into().x as i64;
            if diff < 0 {
                diff += M::m() as i64;
            }
            Modint::new_internal(diff as u64)
        }
    }
    impl<M: Mod, T: Into<Modint<M>>> Mul<T> for Modint<M> {
        type Output = Self;
        fn mul(self, other: T) -> Self {
            Modint::new((self.x * other.into().x) as i64)
        }
    }
    impl<M: Mod, T: Into<Modint<M>>> AddAssign<T> for Modint<M> {
        fn add_assign(&mut self, other: T) {
            *self = *self + other;
        }
    }
    impl<M: Mod, T: Into<Modint<M>>> SubAssign<T> for Modint<M> {
        fn sub_assign(&mut self, other: T) {
            *self = *self - other;
        }
    }
    impl<M: Mod, T: Into<Modint<M>>> MulAssign<T> for Modint<M> {
        fn mul_assign(&mut self, other: T) {
            *self = *self * other;
        }
    }
    impl<M> std::fmt::Display for Modint<M> {
        fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
            self.x.fmt(f)
        }
    }
    impl<M: Mod> From<i64> for Modint<M> {
        fn from(x: i64) -> Self {
            Self::new(x)
        }
    }
    impl<M: Mod> From<i32> for Modint<M> {
        fn from(x: i32) -> Self {
            Self::new(x as i64)
        }
    }
    impl<M: Mod> From<usize> for Modint<M> {
        fn from(x: usize) -> Self {
            Self::new(x as i64)
        }
    }
}
macro_rules! define_mod {
    ($ struct_name : ident , $ modulo : expr ) => {
        #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug)]
        struct $struct_name {}
        impl modint::Mod for $struct_name {
            #[inline]
            fn m() -> u64 {
                $modulo
            }
        }
    };
}
// }}}
//
define_mod!(P, 1_000_000_007);
type Modint = modint::Modint<P>;

fn main() {
    let n = get!(usize);
    let a = get!([i64]);
    let a: Vec<_> = a.iter().map(|x| Modint::new(*x)).collect();
    let sum: Vec<_> = iter::once(Modint::new(0))
        .chain(a.clone())
        .scan(Modint::new(0), |sum, x| {
            *sum = *sum + x;
            Some(*sum)
        })
        .collect();
    let mut ans = Modint::new(0);
    for i in 1..n {
        ans += a[i - 1] * (sum[n] - sum[i]);
    }
    println!("{}", ans);
}


Measured memory_bytes: 9340