#![allow(non_snake_case)]

#[allow(unused_imports)]
use proconio::{input, marker::Usize1, marker::Chars};
#[allow(unused_imports)]
use itertools::Itertools;

#[allow(unused_macros)]
macro_rules! d {
    ( $( $x:expr ),* $(,)? ) => {
        println!(
            concat!( $( stringify!($x), "={:?} " ),* ),
            $( $x ),*
        );
    };
}

fn divmod(a: i64, b: i64) -> (i64, i64) {
    (a.div_euclid(b), a.rem_euclid(b))
}

const MOD: i64 = 1_000_000_007;

fn main() {
    input! {
        N: usize,
    }

    let mut ans: i64 = 0;
    for _ in 0..N {
        input! { C: i64, D: i64 }

        let (d, m) = divmod(C, 2);
        let x = ((d + m) % MOD) * (D % MOD) % MOD;
        ans += x;
        ans %= MOD;
    }

    println!("{}", ans);
}