n,h=map(int,input().split())
a=[]
for i in range(n):
  b,c=map(int,input().split())
  a.append([b,0]);a.append([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:h=0;ans+=(h-1)//a[i][0]+1
print(ans)