N, H = map(int, input().split())
AB = [list(map(int, input().split())) for _ in range(N)]

h = H
strongest = max(AB)

count = 0
for a, b in AB:
	if strongest[0] < b:
		h -= b
		count += 1
		if h <= 0:
			print(count)
			exit()

count += (h // strongest[0]) + (0 != (h % strongest[0]))
print(count)
