#nullable enable

#region
using System.Text.Json.Serialization.Metadata;

var (_input, _iter) = (Array.Empty<string>(), 0);
T I<T>() where T : IParsable<T>
{
    while (_iter >= _input.Length) (_input, _iter) = (Console.ReadLine()!.Trim().Split(' '), 0);
    return T.Parse(_input[_iter++], null);
}
#endregion

static T[] Range<T>(int n, Func<T> F) => Enumerable.Range(0, n).Select(_ => F()).ToArray();

var n = I<int>();
var m = I<long>();
var plants = Range(n, () => (I<long>(), I<long>()));
var limits = new long[n];
for (var i = 0; i < n; i++)
{
    var (a, b) = plants[i];
    limits[i] = (m - a) / b + 1;
}
bool F(int x)
{
    for (var i = 0; i < n; i++)
    {
        var d = i / x + 1;
        if (limits[i] < d) return false;
    }
    return true;
}
Array.Sort(limits);
var pass = n;
var fail = 0;
while (Math.Abs(pass - fail) > 1)
{
    var mid = (pass + fail) >> 1;
    if (F(mid)) pass = mid;
    else fail = mid;
}
Console.WriteLine(pass);