import sys

N, H = [int(x) for x in sys.stdin.readline().strip().split()]
AB = [tuple(int(x) for x in sys.stdin.readline().strip().split()) for i in range(N)]
AB.sort(key=lambda x:(-x[0],x[1]))

p = AB[0][0]
qs = [AB[j][1] for j in range(N) if AB[j][1] > p]
qss, qsl = sum(qs), len(qs)

r = qsl + (H - qss + (p - 1)) // p
print(r)
