n,h=map(int,input().split())
x=[]
for i in range(n):
  a,b=map(int,input().split())
  x.append([a,0])
  x.append([b,1])
x.sort(reverse=1)
i=ans=0
while h>0:
  if x[i][1]:
    h-=x[i][0]
    ans+=1
  else:
    ans+=0--h//x[i][0]
    h=0
  i+=1
print(ans)