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=b=0
while h>0:
  if a[i][1]==1:h-=a[i][0];b+=1
  else:b+=(h-1)//a[i][0]+1;h=0
  i+=1
print(b)