import sys
from typing import List, Tuple
import random

int1 = lambda x: int(x) - 1
# input = lambda: sys.stdin.readline().rstrip('\n')
ii = lambda: int(input())
vi = lambda: list(map(int, input().split()))
vi1 = lambda: list(map(int1, input().split()))


def dbg(*args, **kwargs):
    print(*(repr(arg) for arg in args), *(f'{k}: {repr(v)}' for k, v in kwargs.items()),
          sep='; ', file=sys.stderr, flush=True)


def main():
    n, m = vi()
    ab = [vi() for _ in range(n)]

    d = []
    for a, b in ab:
        d.append((m - a + b - 1) // b)
    d.sort()
    ok = n
    ng = 0
    while ng + 1 != ok:
        mi = (ok + ng) // 2
        for i in range(n):
            if d[i] <= i // mi:
                ng = mi
                break
        else:
            ok = mi
    print(ok)


def _start():
    if (ret := main()) is not None:
        print(*ret) if isinstance(ret, List) or isinstance(ret, Tuple) else print(ret)


if __name__ == '__main__':
    _start()