n,h=map(int,input().split())
a,b=[],[]
for i in range(n):
    j,k=map(int,input().split())
    a.append(j)
    b.append(k)
am=max(a)
bm=[]
for i in b:
    if am<i:bm.append(i)
if sum(bm)<h:print(len(bm)+(h-sum(bm)+am-1)//am)
else:
    bm.sort()
    ans=0
    while h>0:
        h-=bm.pop(-1)
        ans+=1
    print(ans)