n,h=map(int,input().split())
l=sorted([tuple(map(int,input().split())) for _ in range(n)],key=lambda x:-x[1])
th=max(l,key=lambda x:x[0])[0]
v=0
c=0
for i in l:
  if v<h:
    v+=i[1]
    c+=1
  else:
    break
if v<h:
  d=(h-v)//th
  c+=d
  v+=(d*th)
  if v<h:
    v+=th
    c+=1

print(c)