import math

n, h = map(int, input().split())
alist = []
blist = []
for _ in range(n):
    a, b = map(int, input().split())
    alist.append(a)
    blist.append(b)

# aの最大値を求める
amax = max(alist)

# amax以上の刀を投げつける
c = 0
for b in blist:
    if amax < b:
        h -= b
        c += 1
    if h <= 0:
        print(c)
        exit()

# amaxの刀で切りつける
if h > 0:
    c += math.ceil(h / amax)

print(c)
