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

fn main() {
    let mut input = String::new();
    std::io::Read::read_to_string(&mut std::io::stdin(), &mut input).ok();
    let input: Vec<u64> = input
        .split_whitespace()
        .skip(1)
        .map(|n| n.parse().unwrap())
        .collect();

    let mut answer = 0;

    for cd in input.chunks(2) {
        answer += (cd[1] % DIVISOR) * (((cd[0] + 1) / 2) % DIVISOR);
        answer %= DIVISOR;
    }

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