n, h = map(int, input().split())
ab = [list(map(int, input().split())) for i in range(n)]

max_a = 0
for i in ab:
    max_a = max(i[0], max_a)
#print(max_a)

b = [i[1] for i in ab if i[1] > max_a]
#print(b)

count = 0
for i in b:
    h -= i
    count += 1

    if h <= 0:
        print(count)
        exit()

print(count + (h - 1) // max_a)