# /usr/bin/python
# -*- coding: utf-8 -*-
#
import math


def solve(a,b,h):
  ret = 0
  for i in b:
    if h <= 0:
      return ret
    if a < i:
      ret += 1
      h -= i
  ret += math.ceil(h/a)
  return ret


n,h = map(int, input().split())
mx_a = 0
b = [0 for i in range(n)]
for i in range(n):
  a, b[i] = map(int, input().split())
  mx_a = max(mx_a, a)


print(solve(mx_a,b,h))
