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