n,h=map(int,input().split())
AB = [list(map(int, input().split())) for i  in range(n)]
AB = sorted(AB, key=lambda x:x[1])
ans = 0

a = sorted(AB)[-1][0]
for i in range(len(AB)):
  if len(AB) <= 0 or h <= 0:
    break
  b = AB.pop(-1)[1]
  h -= b if b > a else a
  ans += 1

if h > 0:
  ans += (h+a-1)//a

print(ans)