n,h=map(int,input().split())
a=[0 for i in range(n)]
b=[0 for i in range(n)]
ans=0
for i in range(n):
  a[i],b[i]=map(int,input().split())
maxa=max(a)
b=sorted(b,reverse=True)
for i in b:
  if i>maxa:
    ans+=1
    h-=i
  else:
    ans+=(-(-h//maxa))
  if h<0:
    break
print(ans)