import sys
import math
s_ls = sys.stdin.read().split("\n")[:-1]
a = []
b = []
hp = int(s_ls[0].split()[1])
max_slash = 0
for element in s_ls[1:]:
    slash = int(element.split()[0])
    if slash > max_slash:
        max_slash = slash
    b.append(int(element.split()[1]))
bp = sorted([x for x in b if x > max_slash])[::-1]
count = 0
for e in bp:
    hp -= e
    count += 1
    if hp < 0:
        break
if hp > 0:
    count += math.ceil(hp / max_slash)

print(count)