
s=raw_input().split(' ')
n=int(s[0])
h=int(s[1])

mx=0
ar=[]
for i in range(n):
	s=raw_input().split(' ')
	a=int(s[0])
	b=int(s[1])
	if a>mx:
		mx=a;
	ar.append(b)

v=0
s=0
for i in range(len(ar)):
	if ar[i]>=mx:
		s=s+ar[i];
		v=v+1;

c=(h-s);
if c%mx==0:
	v+=(c/mx)
else:
	v+=(c/mx)+1
print(v)