n, h = map(int, input().split())
ls = [list(map(int, input().split())) for _ in range(n)]
a = max([l[0] for l in ls])
bs = [l[1] for l in ls if l[1] > a]
bs.sort()
res = 0
while h > 0 and len(bs) > 0:
    h -= bs.pop()
    res += 1
if h > 0:
    res += (h + a - 1) // a
print(res)