n, h, *k = map(int, open(0).read().split())
a = max(k[::2]); b = sorted(k[1::2], reverse = True)

ans = 0
while ans < n and b[ans] > a and h > 0:
    h -= b[ans]
    ans += 1
if h > 0: ans += (h + a - 1) // a
print(ans)