#include <bits/stdc++.h>
using namespace std;
#define rep1(a)          for (int i = 0; i < (a); i++)
#define rep2(i, a)       for (int i = 0; i < (a); i++)
#define rep3(i, a, b)    for (int i = a; i < (b); i++)
#define rep4(i, a, b, c) for (int i = a; i < (b); i += c)
#define overload4(a, b, c, d, e, ...) e
#define rep(...) overload4(__VA_ARGS__, rep4, rep3, rep2, rep1)(__VA_ARGS__)
using ll = long long;
constexpr ll INF = (1LL << 60);
void chmax(ll& a, ll b) { a = max(a, b);}
void chmin(ll& a, ll b) { a = min(a, b); }
inline void YesNo(bool ok) {
  cout << (ok ? "Yes\n" : "No\n");
}
template<class T>
void input_vec(vector<T>& v) {
  for (auto& x : v) cin >> x;
}
template<class... T>
void input(T&... a) {
  (cin >> ... >> a);
}
void print() {
  cout << '\n';
}
template<class T, class... Ts>
void print(const T& a, const Ts&... b) {
  cout << a;
  (cout << ... << (cout << ' ', b));
  cout << '\n';
}

int main() {
  ios::sync_with_stdio(false);
  cin.tie(nullptr);

  int n, m;
  cin >> n >> m;
  map<int, int> M;
  rep(i, n) {
    int a, b;
    cin >> a >> b;
    M[(m-a+b-1)/b]++;
  }
  int sum = 0;
  int k = 0;
  for (auto j : M) {
    sum += j.second;
    k = max(k, (sum+j.first-1)/j.first);
  }
  cout << k << endl;
  return 0;
}