use std::collections::BTreeMap;

use proconio::input;

fn main() {
    input! {
        (n, m): (usize, u64),
        ab: [(u64, u64); n],
    }

    let graces = ab.iter().map(|&(a, b)| (m - a) / b + 1);
    let mut grace_map = BTreeMap::<u64, usize>::new();
    for grace in graces {
        *grace_map.entry(grace).or_default() += 1;
    }

    let mut k = 0;
    let mut acc = 0;
    for (grace, cnt) in grace_map {
        acc += cnt;
        k = k.max((acc + grace as usize - 1) / grace as usize);
    }

    println!("{k}");
}