#include <iostream>
#include <cstring>
#include <algorithm>

using namespace std;

const int N = 1e5 + 5;

int n, h;
struct Knife {
    int damage, num;
    bool operator<(const Knife& b) const {
        return damage > b.damage;
    }
} a[N];

int main() {
    ios::sync_with_stdio(false), cin.tie(0), cout.tie(0);
    cin >> n >> h;
    int tot = 0;
    for (int i = 1; i <= n; i++) {
        cin >> a[tot].damage; a[tot++].num = 0;
        cin >> a[tot].damage; a[tot++].num = 1;
    }

    int res = 0;
    sort(a, a + tot);
    for (int i = 0; i < tot; i++) {
        if (a[i].num) {
            h -= a[i].damage;
            res++;
            if (h <= 0) {
                cout << res << endl;
                return 0;
            }
        } else {
            if (h % a[i].damage == 0) res += (h / a[i].damage);
            else res += (h / a[i].damage + 1); 
            cout << res << endl;
            return 0;
        }
    }
    return 0;
}

样例都过了