# -*- coding: utf-8 -*-

from math import ceil

n, h = map(int, input().split())
a_li = []
b_li = []
for _ in range(n):
    a, b = map(int, input().split())
    a_li.append(a)
    b_li.append(b)

a_max = max(a_li)
b_li.append(a_max)
b_li.sort()

cnt = 0
while True:
    b_max = b_li.pop()
    if b_max == a_max:
        cnt += ceil(h / a_max)
        break
    else:
        h -= b_max
        cnt += 1

print(cnt)
