n, h = list(map(int, input().split()))

wield = 0
bs = []

for i in range(n):
    a, b = list(map(int, input().split()))

    if a > wield:
        wield = a

    bs.append(b)

throw = 0
throwCnt = 0

for i in range(n):
    if bs[i] > wield:
        throw += bs[i]
        throwCnt += 1

print(max((h-throw+wield-1)//wield + throwCnt, 1))