# -*- coding: utf-8 -*-
"""
Created on Tue Jun 19 03:01:30 2018

@author: ashida
"""

N, H = map(int, input().split())

A_max = 0
D_seq = []

for i in range(N):
    A, D = map(int, input().split())
    if A>A_max:
        A_max = A
    D_seq.append(D)

D_sum = 0
D_count = 0

for i in range(N):
    if D_seq[i] > A_max and D_sum < H:
        D_sum += D_seq[i]
        D_count += 1

A_sum = H-D_sum

if A_sum%A_max == 0:
    print(A_sum//A_max + D_count)
else:
    print(A_sum//A_max + D_count+1)