import sys

input = sys.stdin.readline

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

slash_throw = [[int(x) for x in input().split()] for _ in range(N)]

slashs = []
throws = []

for slash, throw in slash_throw:
    slashs.append(slash)
    throws.append(throw)

max_slash = sorted(slashs)[-1]
remaining_hp = H
attack_count = 0

for throw in throws:
    if throw > max_slash:
        remaining_hp -= throw
        attack_count += 1
        if remaining_hp <= 0:
            break

if remaining_hp > 0:
    attack_count += -(remaining_hp // -max_slash)

print(attack_count)