import numpy as np
import math
N, H = map(int, input().split())
ab = [list(map(int, input().split())) for i in range(N)]
ab = np.array(ab)
attack = 0

furu = np.argmax(ab[:,0])
furupower = ab[furu,0]
nageru = np.argmax(ab[:,1])
nagerupower = ab[nageru,1]

#投げる
while not(furupower >= nagerupower or furu == nageru):
    H -= nagerupower
    ab = np.delete(ab, nageru, 0)
    furu = np.argmax(ab[:,0])
    furupower = ab[furu,0]
    nageru = np.argmax(ab[:,1])
    nagerupower = ab[nageru,1]
    attack += 1
#振る
attack += math.ceil((H - nagerupower)/furupower)
#投げる
if H > 0:
    attack += 1
print(attack)
