# -- coding: utf-8 --
import math
N, H = map(int, input().split())
sl = []
th = []
for i in range(N):
    s, t = map(int, input().split())
    sl.append(s)
    th.append(t)
turn = 0
thm = list(filter(lambda x:x>max(sl), th))
thdec = sorted(th, reverse=True)

if sum(thdec) >= H:
    while H > 0:
        H = H - max(thdec)
        thdec.pop(0)
        turn += 1
else:
    turn = math.ceil((H - sum(thm)) / max(sl)) + len(thm)

print(turn)