import math
N,H = map(int,input().split())
l = []
for i in range(1,N+1):
  l.append(list(map(int,input().split())))

[A,B] = max(l)
l.remove([A,B])
nage = []
for i in range(N-1):
  if l[i][1] > A:
    nage.append(l[i][1])
if B > A:
  nage.append(B)    

cnt = 0
for i in range(len(nage)):
  H -= nage[i] 
  if H <= 0:
    cnt = i+1
    break   
  if i == len(nage)-1:
    if B > A:
      H += B
      cnt = len(nage)-1
      H -= B
      cnt += max(0,math.ceil(H/A))+1
    else:
      cnt = len(nage)
      cnt += math.ceil(H/A)
print(cnt)    