num, hp = (int(i) for i in input().split(" "))

katanas_a = []
katanas_b = []

for i in range(num):
    a, b = (int(j) for j in input().split(" "))
    katanas_a.append(a)
    katanas_b.append(b)

katanas_a.sort()
swing_max = katanas_a[len(katanas_a) - 1]

attack_count = 0
for katana in katanas_b:
    if katana > swing_max:
        hp -= katana
        attack_count += 1

count = hp % swing_max

if hp % swing_max != 0:
    attack_count += int(hp / swing_max) + 1
else:
    attack_count += int(hp / swing_max)

print(attack_count)