from math import ceil
n, h = map(int, raw_input().split())
s = []
for x in xrange(n):
    ta, tb = map(int, raw_input().split())
    s.extend([(ta, 1), (tb, 0)])
s.sort(key = lambda _: _[0], reverse = True)
att = 0
for i, _ in enumerate(s):
    if att >= h or _[1]:
        cnt = i
        break
    att += _[0]
print cnt + int(ceil(float(h - att) / max([_[0] for _ in s if _[1]]))) if att < h else cnt
