#include <bits/stdc++.h>
using namespace std;

int main() {
    int N, M;
    cin >> N >> M;
    vector<int> A(N), B(N);
    vector<int> vec(N);
    for (int i = 0; i < N; i++) {
        cin >> A[i] >> B[i];
        vec[i] = (M - A[i]) / B[i] + 1;
    }
    sort(vec.begin(), vec.end());
    auto check = [&](int m) -> bool {
        int day = 1;
        int cur = 0;
        while (cur < N) {
            for (int i = 0; i < m && cur + i < N; i++) {
                if (vec[cur + i] < day) {
                    return false;
                }
            }
            cur += m;
            day++;
        }
        return true;
    };
    int ok = N, ng = 0;
    while (abs(ok - ng) > 1) {
        int mid = (ok + ng) / 2;
        if (check(mid)) {
            ok = mid;
        } else {
            ng = mid;
        }
    }
    cout << ok << endl;
}