import heapq
import math
def main():
  N, H = map(int, input().split())
  A = 0
  B = []
  for i in range(N):
    a, b = map(int, input().split())
    A = max(A, a)
    B.append(-1*b)
  ans = math.ceil(H/A)
  wa = ans*A
  heapq.heapify(B)
  while True:
    temp = -1*heapq.heappop(B)
    if temp > A:
      wa = wa-A +temp
      if wa - H >= A:
        ans-= (wa-H)//A
        wa-= ((wa-H)//A)*A
    if temp < A or len(B) == 0:
      break
  print(ans)
if __name__ == "__main__":
  main()