n, h = map(int, raw_input().split())
a, b = [], []
for x in xrange(n):
    ta, tb = map(int, raw_input().split())
    a.append(ta)
    b.append(tb)
ma = max(a)
o = [_ for _ in b if _ > ma]
rest = h - sum(o)
print len(o) + rest / ma + int(bool(rest % ma))