n,h=map(int,input().split())
l=[tuple(map(int,input().split())) for _ in range(n)]
th=max(l,key=lambda x:x[0])[0]
l=sorted([i for i in l if i[1]>=th],key=lambda x:-x[1])
c,v=0,0
for i in l:
  if v<h:
    v+=i[1]
    c+=1
if v<h:
  a,b=divmod(h-v,th)
  if b:a+=1
  c+=a
print(c)