import math

damage = 0
count = 0

n, h = map(int, input().split(' '))
a = []
b = []
for _ in range(n):
    temp = input().split(' ')
    a.append(int(temp[0]))
    b.append(int(temp[1]))
    
for x in b:
    if x >= max(a):
        damage += x
        count += 1

count += math.ceil(((h - damage) / max(a))

print(count)