n,h=map(int,input().split())
ab=[list(map(int,input().split())) for i in range(n)]
b=[ab[i][1] for i in range(n)]
b.sort(reverse=True)
cnt=0
ab.sort(key=lambda x:x[0],reverse=True)
k=0
while k<n and ab[0][0]<b[k] and h>0:
  h-=b[k]
  k+=1
  cnt+=1
if h>0:
  cnt+=(h+ab[0][0]-1)//ab[0][0]
print(cnt)