import math

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

az, bz = list(zip(*ab))
maxa = max(az)
minb = min(bz)
cnt = 0
for i in bz:
    if i > maxa:
        h -= i
        cnt += 1
if h >= 0:
    cnt += math.ceil(h / maxa)
print(cnt)
