N,H=map(int,raw_input().split())
c=[]
for i in range(N):
	a,b=map(int,raw_input().split())
	c.append((a,0))
	c.append((b,1))

c.sort(key=lambda x:x[0],reverse=True)

cnt=0
for i,j in c:
	if j==1:
		H-=i
		cnt+=1
		if H<=0:
			break
	else:
		if H%i==0:
			cnt+=H/i
			break
		else:
			cnt+=H/i+1
			break
print cnt


