N, H = ( int(i) for i in input().split() )
ka = []
kb = []
for i in range(N):
	a, b = ( int(i) for i in input().split() )
	ka.append(a)
	kb.append(b)
	
kb.sort()
kb.reverse()

hp = H
res = 0
for b in kb:
	hp = hp - b
	res += 1
	if hp <= 0:
		break
else:
	res += (hp + max(ka) - 1)//max(ka)
	
print(res)
		