import math

Num,HP = (map(int,input().split()))
Katanas = [list(map(int,input().split())) for x in range(Num)]

amax = max([x[0] for x in Katanas])
bpower = [x[1] for x in Katanas if x[1] > amax]
bsum = sum(bpower)
attake = math.ceil((HP-bsum)/amax)+len(bpower)
print(attake)